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Etsi isup inap_iw_book

  1. 1. NT Europe SIM Specification DMS Implementation of ETSI ISUP / INAP interworking Release 4 ETSI ISUP/INAP Interworking SIM Date: Version: 13 December 1996 PRE 0.2 (draft) Originated by: BNR Department EP11 Classification: RESTRICTED Activity ID: 10-95-0070 NIS number: 94-80nn Acknowledgements: 7020 Design Team
  2. 2. Notice This document and the information contained herein is provided “as is” with no warranty of any kind, expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for any particular purpose. The entire risk as to quality and performance of the information provided is with the user. Should the information prove defective, the user assumes the cost of all necessary servicing, repair, or correction. In no event is Northern Telecom liable for any damages, direct, indirect, or consequential. Northern Telecom may, but is not obliged to, update the information, or arrange for the information to be updated, and make the updates available to users from time to time. Release Process This document adheres to the Strategic Interface Management (SIM) process. The SIM process is an administrative process developed to manage the evolution of interface specifications through authorisation, approval and verification stages. The four stages of an interface document that follows the SIM process are: PRE: This is the initial recommendation. The prefix PRE indicates that this document is at a preliminary stage, and as such should be treated as a ‘draft’ document. External distribution is limited. AUT: Following the authorisation of the document by NT and BNR design the prefix of the revision status is promoted to AUT. AUT implies that the document has been fully authorised and that it represents the agreed interface product undergoing development. APP: Upon completion of the design and test of the interface product the prefix of the document is promoted to APP. At this stage the document broadly relates to BCS IS quality. VER: Following final verification of the interface in the field, the document's prefix is promoted to VER. This document represents the final release of the interface product in its current version.
  3. 3. Document signoff BNR Design Approval Kathy Shaw Senior Manager, WT IN Development (7020) Signature: Date: BNR Planning Approval Iain Donaldson Senior Manager, Product Planning Switching (EP10) Signature: Date: NT Product Management Approval David Ainsworth Director, Product Line Management Signature: Date:
  4. 4. Change history Version Date of Release Summary of Changes PRE 0.1 (draft) 11 October 1996 First release of preliminary draft for internal Planning review and limited distribution outside Planning. Draft based on Release 4 IBN7 interworking spec. PRE 0.2 (draft) 13 December 1996 Incorporate ETSI ISUP review comments, and relevant comments from BTUP review.
  5. 5. NIS 94-80nn World Trade IN Release 4 ETSI ISUP/INAP Interworking PRE 0.2 (draft) Preface 13 December 1996 Page v Preface Purpose This document is a Strategic Interface Management (SIM) specification for the World Trade Intelligent Network (IN) project. The aim of the project is to plan and develop a DMS Service Switching Point (SSP), i.e. software that will enable a DMS-100E to provide IN SSP functionality as well as its usual network functions. The purpose of this issue of the document is to describe accurately the interworking features of Release 4 of the DMS SSP product. Features introduced in Release 4 are: • Support for the bearerCapability parameter of the INAP operation IntialDP • Support for an Ethernet Link Interface Unit, which allows CCS7 messages to be encapsulated in TCP/IP packets and sent over an Ethernet Local Area Network Content This document describes DMS SSP support for interworking between ETSI ISUP and the Intelligent Network Application Part (INAP). Such interworking enables the DMS SSP to support IN services for calls that originate in the PSTN and arrive at the DMS SSP via ETSI ISUP trunks.
  6. 6. Release 4 ETSI ISUP/INAP Interworking World Trade IN NIS 94-80nn Preface PRE 0.2 (draft) Page vi 13 December 1996 Structure The specification is organised into the following sections: • Section 1: Introduction on page 1 • Section 2: Triggering IN Interaction on page 15 • Section 3: Call Processing Suspended on page 31 • Section 4: Call Processing Resumed on page 53 • Section 5: Service Filtering on page 61 There are also appendices that provide detailed information about the mapping of parameters between ETSI ISUP messages and INAP operations. Readership The specification is intended to serve three purposes: • To provide a functional view of ETSI ISUP / INAP interworking that will enable BNR Planning and NT Marketing to assess its applicability for potential customers. • To examine possible implementations of the interworking and compare these with current and planned DMS SSP capabilities. This will enable BNR Planning, BNR Design and NT Product Management to decide on the best method of supporting the interworking. • To define all the requirements of the agreed implementation method to a level of detail sufficient to enable BNR Design to build it, and to serve as the definitive BNR and NT source of reference information on the interworking after it has been built. The specification will be subject to regular review, and will be updated to incorporate comments, to capture new information, and to reflect evolving requirements for ETSI ISUP / INAP interworking within the World Trade IN project.
  7. 7. NIS 94-80nn World Trade IN Release 4 ETSI ISUP/INAP Interworking PRE 0.2 (draft) Preface 13 December 1996 Page vii References Related World Trade IN Documents [1] NIS 94-8000 World Trade IN Document Roadmap [2] NIS 94-8008 DMS Implementation of CS-1R INAP (ETSI Core INAP Subset) [3] AG5307 Ethernet LIU [4] AG5313 Bearer Capability [5] DMS SSP Product Description Technical References [6] ETS 300 374-1 ETSI specification of Core INAP for IN Capability Set 1 [7] Q.1214 Distributed Functional Plane for Intelligent Network CS-1 [8] Q.1218 Interface Recommendation for Intelligent Network CS-1 [9] Q.1224 Distributed Functional Plane for Intelligent Network CS-2 [10] Q.1228 Interface Recommendation for Intelligent Network CS-2 [11] Q.771 to Q.775 ITU-T TCAP specifications (Blue Book) [12] Q.711 to Q.714 ITU-T SCCP specifications (Blue Book) [13] Q.701 to Q.704 ITU-T MTP specifications (Blue Book) NT/BNR Process Documentation used by BNR Planning [14] NQAPR102 Strategic Interface Management (SIM) Process [15] NQAPR103 Document Control Process [16] NQAPR104 Document Review Process
  8. 8. Release 4 ETSI ISUP/INAP Interworking World Trade IN NIS 94-80nn Preface PRE 0.2 (draft) Page viii 13 December 1996
  9. 9. NIS 94-80nn World Trade IN Release 4 ETSI ISUP/INAP Interworking PRE 0.2 (draft) Abbreviations 13 December 1996 Page ix Abbreviations ACM Address Complete Message (ETSI ISUP) AMA Automatic Message Accounting ANM Answer Message (ETSI ISUP) ANSI American National Standards Institute ASF ActivateServiceFiltering (INAP operation) AUT AUThorised for release BCSM Basic Call State Machine CCF Call Control Function CCS7 Common Channel Signalling System No 7 CDR Call Detail Recording CIRP CallInformationReport (INAP operation) CIRQ CallInformationRequest (INAP operation) CS-1 Capability Set 1 (for IN) CS-2 Capability Set 2 (for IN) CTR ConnectToResource (INAP operation) DFC DisconnectForwardConnection (INAP operation) DMS Digital Multiplex System DP Detection Point DRAM Digital Recorded Announcement Machine DTC Digital Trunk Controller EDP Event Detection Point EDRAMEnhanced (single-card) DRAM ELIU Ethernet Link Interface Unit ERB EventReportBCSM (INAP operation) ETC EstablishTemporaryConnection (INAP operation) ETSI European Telecommunications Standards Institute (CEPT standards body) FCI FurnishChargingInformation (INAP operation) FN Functional Specification FSM Finite State Machine IAM Initial Address Message (ETSI ISUP) IDP InitialDP (INAP operation) IN Intelligent Network INAP Intelligent Networks Applications Part IP Intelligent Peripheral ISDN Integrated Services Digital Network
  10. 10. Release 4 ETSI ISUP/INAP Interworking World Trade IN NIS 94-80nn Abbreviations PRE 0.2 (draft) Page x 13 December 1996 ISUP ISDN User Part (part of CCS7) ITU International Telecommunications Union LE Local Exchange MTP Message Transfer Part (part of CCS7) NT Northern Telecom NUP National User Part OAM Operations, Administration and Maintenance OSI Open Standard for Interconnection P&C PromptAndCollectUserInformation (INAP operation) PA PlayAnnouncement (INAP operation) PDU Protocol Data Unit PIC Point In Call POTS Plain Ordinary Telephone Service PRE PREliminary status PRI ISDN Primary Rate Interface PSTN Public Switched Telephone Network RES Resume message (ETSI ISUP) RRBE RequestReportBCSMEvent (INAP operation) RT ResetTimer (INAP operation) SAM Subsequent Address Message (ETSI ISUP) SCCP Signalling Connection Control Part (part of CCS7) SCF Service Control Function SCP Service Control Point SDL State (machine) Description Language SDT SDL Tool SFR ServiceFilteringResponse (INAP operation) SIM Strategic Interface Management SRF Specialised Resource Function SRR SpecializedResourceReport (INAP operation) SRSM Specialised Resource State Machine SSF Service Switching Function SSME SSF Management Entity SSN Subsystem Number (identifies CCS7 user or application part within node) SSP Service Switching Point STP Signalling Transfer Point SUS Suspend (ETSI ISUP message) TCAP Transaction Capabilities Application Part TDP Trigger Detection Point
  11. 11. NIS 94-80nn World Trade IN Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Table of Contents 13 December 1996 Page xi Table of Contents Preface v Abbreviations ix Table of Contents xi 1 Introduction 1 1.1 The Need for Interworking 1 1.1.1 Access Signalling and IN Signalling 1 1.1.2 Terminating Signalling 2 1.1.3 External IP Signalling 2 1.1.4 Functional Elements Involved in Interworking 3 1.2 DMS SSP Support for IN capabilities 5 1.2.1 INAP Operation Support 5 1.2.2 BCSM Support 6 1.2.2.1 Overview of the BCSM 6 1.2.2.2 Detection Point Types 7 1.2.2.3 DMS SSP Support for TDPs 8 1.2.2.4 DMS SSP Support for EDPs 8 1.3 DMS SSP Support for ETSI ISUP 9 1.4 Overview of ETSI ISUP / INAP Interworking 9 1.4.1 IN Interaction Involving the SCF 10 1.4.2 IN Interaction Handled by SSF (Service Filtering) 12 2 Triggering IN Interaction 15 2.1 Introduction 15 2.2 IN Interaction with ETSI ISUP En-Bloc Signalling 16 2.2.1 Overview of En-Bloc Signalling 16 2.2.2 Sequence of Events 17 2.2.2.1 Call Arrival (PIC_1) 17 2.2.2.2 Digit Collection (PIC_2) 18 2.2.2.3 Triggering at TDP-2 (Collected Info) 18 2.2.2.4 Digit Translation (PIC_3) 18 2.2.2.5 Triggering at TDP-3 (Analysed Info) 18
  12. 12. NIS 94-80nn World Trade IN Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Table of Contents 13 December 1996 Page xii 2.2.2.6 Trigger Processing 19 2.2.2.7 Initiating IN Interaction 20 2.3 IN Interaction with ETSI ISUP Overlap Signalling 21 2.3.1 Overview 21 2.3.2 Sequence of Events 21 2.3.2.1 Call Arrival (PIC_1) 22 2.3.2.2 Digit Collection (PIC_2) 23 2.3.2.3 Triggering at TDP-2 (Collected Info) 23 2.3.2.4 Digit Translation (PIC_3) 24 2.3.2.5 Triggering at TDP-3 (Analyzed Info) 24 2.3.2.6 Trigger Processing 25 2.3.2.7 Initiating IN Interaction 29 2.4 Feature interaction Before First IN trigger 29 2.5 Error handling 30 2.5.1 Errors Detected by INAP 30 2.5.2 Timer Expiry 30 2.5.3 Errors Detected by TCAP 30 2.5.4 Errors Detected by ETSI ISUP 30 3 Call Processing Suspended 31 3.1 Overview 31 3.2 Billing 32 3.2.1 AMA Billing Records 32 3.3 User Interaction 33 3.3.1 INAP Operations Used 33 3.3.2 User Interaction Using an Integrated IP 35 3.3.2.1 Message Flow Overview 35 3.3.2.2 Sequence of Events 38 3.3.3 User Interaction Using an External IP 39 3.3.3.1 Message Flow Overview 39 3.3.3.2 Sequence of Events 42 3.4 Resumption of O_BCSM call processing 44 3.4.1 Call Completion (Connect) 44 3.4.2 Call Clearing (ReleaseCall) 46 3.5 Error Handling 46 3.5.1 Errors Detected by INAP 46 3.5.1.1 Errors Detected by the SCF 46 3.5.1.2 Errors Detected by the SSF/SRF 46 3.5.2 Timer Expiry 47 3.5.2.1 Expiry of TSSF 48 3.5.2.2 Expiry of TSRF 49 3.5.3 Errors Detected by TCAP 50 3.5.3.1 Errors Detected by the SCF 50 3.5.3.2 Errors Detected by the SSF 50 3.5.4 User-Initiated Abort 50 3.5.5 Errors Detected by ETSI ISUP 51
  13. 13. NIS 94-80nn World Trade IN Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Table of Contents 13 December 1996 Page xiii 4 Call Processing Resumed 53 4.1 Call Completion (after Connect) 53 4.2 Call Clearing (after ReleaseCall) 55 4.3 Returning Requested Call Information 56 4.4 Monitoring 56 4.4.1 Monitoring for DP-4 (Route_Select_Failure) 57 4.5 Error Handling 58 4.5.1 Errors Detected by INAP 58 4.5.1.1 Errors Detected at the SCF 58 4.5.1.2 Errors Detected at the SSF or SRF 58 4.5.2 Timer Expiry 58 4.5.3 Errors Detected by TCAP 58 4.5.3.1 Errors Detected at the SCF 58 4.5.3.2 Errors Detected at the SSF or SRF 60 4.5.4 Errors Detected by ETSI ISUP 60 5 Service Filtering 61 5.1 Activation of Service Filtering 61 5.2 Call Processing during Service Filtering 63 5.2.1 Overview 63 5.2.2 Sequence of Events for a Filtered IN Call 63 5.3 Termination of Service Filtering 66 5.4 Error Handling 66 5.4.1 Errors Detected by INAP 66 5.4.1.1 Errors Detected at the SCF 66 5.4.1.2 Errors Detected at the SSF or SRF 67 5.4.2 Timer Expiry 67 5.4.3 Errors Detected by TCAP 67 5.4.4 Errors Detected by ETSI ISUP 67 A Forward Setup (IAM to InitialDP) 69 A.1 Mappings between Parameters 69 A.2 Deriving INAP Parameter Values from ETSI ISUP 69 A.2.1 ServiceKey 70 A.2.2 EventTypeBCSM 70 A.2.3 CallingPartysCategory 70 A.2.4 CalledPartyNumber 70 A.2.5 CallingPartyNumber 71 A.2.6 BearerCapability 71 A.2.7 Extensions 72 B Forward Setup (Connect to IAM) 73 B.1 Mappings between Parameters 73 B.2 Deriving ETSI ISUP Parameter Values from INAP 74 B.2.1 DestinationRoutingAddress/CutAndPaste -> Called Party Number 74
  14. 14. NIS 94-80nn World Trade IN Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Table of Contents 13 December 1996 Page xiv B.2.2 CallingPartysCategory 75 B.2.3 Extensions 75 C Backward Setup (ACM and ANM) 77 D PRI Interworking for External IP Connection 79 D.1 Establishing a Connection 79 D.1.1 Deriving PRI Parameter Values from INAP 80 D.1.1.1 assistingSSPIPRoutingAddress --> Called Party Number 80 D.1.1.2 correlationID --> User to User Information 80 D.2 Terminating a Connection 82 D.3 Interworking Restrictions 83 E Call Clearing Parameters 85 E.1 Mapping INAP Cause Values 85 E.2 Call Clearing Initiated by DMS SSP 86 E.2.1 SCP Sends ReleaseCall 86 E.2.2 SCP Sends DisconnectLeg 86 E.2.3 Routing Failure Within the DMS SSP 86 E.3 Call Clearing Initiated Elsewhere 87 E.3.1 Calling Party Disconnects Before Call is Completed 87 E.3.2 Call Fails to Complete After Connect 87
  15. 15. NIS 94-80nn World Trade IN Section 1: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Introduction 13 December 1996 Page 1 1 Introduction 1.1 The Need for Interworking 1.1.1 Access Signalling and IN Signalling Support for interworking between the following types of signalling is a prerequisite for Intelligent Networking (IN): • IN signalling, i.e. the interface used for inter-node signalling between IN functions. This is the Intelligent Network Application Part (INAP). • IN access signalling, i.e. interfaces over which IN functionality is accessed from the underlying network (e.g. PSTN, VPN). The access signalling interface considered in this specification is ETSI ISUP Version 1 (referred to in this document simply as ETSI ISUP). This specification describes DMS SSP support for interworking between ETSI ISUP and INAP. Such interworking enables the DMS SSP to support IN services for calls that arrive at the DMS SSP via ETSI ISUP trunks, as shown in Figure 1. INAP and ETSI ISUP are both Common Channel Signalling System No7 (CCS7) interfaces. INAP is the top layer of a CCS7 Blue Book protocol stack comprising the Transaction Capabilities Application Part (TCAP), the Signalling Connection Control Part (SCCP) and the Message Transfer Part (MTP); INAP operations are conveyed in TCAP components within MTP Message Signal Units (MSUs). ETSI ISUP uses only the MTP; ETSI ISUP messages are packaged directly in MSUs. In protocol terms, interworking between ETSI ISUP and INAP involves (but is not limited to) mapping INAP operations and ETSI ISUP messages.
  16. 16. Section 1: World Trade IN NIS 94-80nn Introduction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 2 13 December 1996 Figure 1 Interworking between access signalling and IN signalling Subscribers access the IN by means of basic calls. IN service calls are initially distinguished from non-IN calls on the same ETSI ISUP trunks, which require normal call processing, by means of the digits dialled by the calling party. Special numbers (e.g. an 0800 FreePhone number or equivalent) are recognised as requiring IN processing by comparing them with trigger criteria held at the switch. If a match occurs, the call triggers and IN processing is initiated. The ETSI ISUP Basic Call State Machine (BCSM) then waits for the result of the IN interaction before routing the call to its final destination. 1.1.2 Terminating Signalling If IN interaction results in a call being routed on through the PSTN, outward call completion may take place either over the access signalling system (ETSI ISUP) or over any other signalling system with which the access signalling system can interwork (see the DMS-SSP Product Description for a list of the signalling systems with which ETSI ISUP can interwork). 1.1.3 External IP Signalling If an external Intelligent Peripheral (IP) is used (e.g. for collecting further information from the user, for playing announcements to the user, or to provide speech recognition facilities), a connection is set up between the DMS SSP and the external IP over an ETSI PRI trunk. Tandem or local switch SCP IN IN PSTN DMS SSP Access signalling ETSI ISUP/INAP point interworking (e.g. ETSI ISUP) signalling (INAP) Call can be routed onward to any ETSI ISUP-compatibleinterface External IPPRI ELIU SCPTCP/IP CCS7
  17. 17. NIS 94-80nn World Trade IN Section 1: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Introduction 13 December 1996 Page 3 Note: Although Figure 1 shows an external IP directly connected to the DMS SSP, the connection need not be direct. Although the outgoing trunk from the DMS SSP will be ETSI PRI, setting up a link to an external IP may involve interworking with other agents. However, depending on how the address of the external IP is specified, there may be restrictions on interworking; see Appendix D for details. 1.1.4 Functional Elements Involved in Interworking An intelligent network is defined to consist of functional elements (also referred to as functional entities or simply functions) that have the following characteristics: • Each functional element is clearly defined at a logical level as a state machine (or a set of related state machines). • A given functional element is always allocated to a single physical node, but a given node may accommodate two or more functional elements. • Communication within the IN is defined in terms of information flows between functional elements (which cause changes to the respective state machines), rather than in terms of messages between nodes. Functional elements on different nodes communicate using INAP. The following list defines the most important IN functional elements: SCF Service Control Function Typically, an IN service is implemented by means of service logic and a database under SCF control. The role of the SCF is to respond to service requests from the SSF, e.g. by providing routing information that makes it possible to complete a call. The SCF is usually allocated to an SCP (Service Control Point) node. The DMS SSP uses INAP to communicate with an SCF on an SCP. Note: As a low cost alternative to supplying a CCS7 interface between the DMS SSP and the SCP, the DMS SSP supports an Ethernet Link Interface Unit (ELIU), which allows CCS7 messages to be encapsulated in TCP/IP packets for transmission to a ServiceBuilder SCP connected via an Ethernet Local Area Network. SSF Service Switching Function The SSF provides the interface between the PSTN and the IN. Its key tasks are to recognise PSTN calls that require IN service processing, and to interact with CCF call processing and SCF service logic to ensure that those calls are successfully completed. The SSF is usually allocated to an SSP (Service Switching Point) node. The DMS SSP supports an SSF Finite State Machine (FSM).
  18. 18. Section 1: World Trade IN NIS 94-80nn Introduction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 4 13 December 1996 SRF Specialised Resource Function The SRF provides any specialised resources that are required for interaction with the end user, either to provide information or to obtain it. Information is typically provided in the form of announcements or tones, and is typically collected as dialled digits. The SRF is logically allocated to an Intelligent Peripheral (IP), which may be integrated with an SSP or may be a separate node attached to an SSP. The DMS SSP supports an integrated IP, in which the DMS switch itself provides features for digit collection and playing recorded announcements. The DMS SSP also supports connections to an external IP, which provides SRF-type services. The DMS SSP uses a PRI trunk to set up a link to the external IP, which can then communicate directly with the SCP without further involvement by the DMS SSP. CCF Call Control Function The CCF is not, strictly speaking, an IN functional element, but a standard Basic Call State Machine (BCSM) for which trigger criteria are defined that determine the conditions under which a given call requires IN service access. Because it interacts closely with the SSF, the CCF usually resides with the SSF in an SSP node. The DMS SSP supports CCF functions by means of a ETSI ISUP BCSM with access to trigger tables that specify which dialled digits will initiate IN service access. Figure 2 shows how these functional elements, particularly those implemented on the DMS SSP, interact to support interworking. Figure 2 Interaction between IN functional elements to support interworking Note: Although Figure 2 shows an external IP directly connected to the DMS SSP, the connection need not be direct. Although the outgoing trunk from the DMS SSP will be ETSI PRI, setting up a link to an external IP may involve interworking with other agents. DMS SSP SCP INAP ETSI ISUP SSF SCF CCF Terminating interface/agent SRF Interworking External IP PRI SRF Integrated IP INAP
  19. 19. NIS 94-80nn World Trade IN Section 1: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Introduction 13 December 1996 Page 5 1.2 DMS SSP Support for IN capabilities The DMS SSP implementation of IN is based on ITU-T CS-1R (Capability Set 1) procedures and the ETSI Core INAP protocol. Its support for IN capabilities can be summarised under two headings: • Support for the INAP operations defined in Q.1218 and ETS 300 374-1 • Support for the Basic Call State Machine (BCSM) defined in Q.1214 1.2.1 INAP Operation Support ETS 300 374-1 defines a total of 29 Core INAP operations (these are a subset of the operations defined in Q.1218). The operations supported by the DMS SSP can be roughly divided into the following categories: • Call setup operations for single-stage calls (no user interaction required): InitialDP Connect • Call setup operations for two-stage calls (with SCP-initiated user interaction): ConnectToResource EstablishTemporaryConnection PromptAndCollectUserInformation PlayAnnouncement SpecializedResourceReport DisconnectForwardConnection The ConnectToResource operation is used to set up a connection to the DMS SSP’s integrated IP. With such a connection there is no direct communication between the SCF and the SRF. The SSF can be regarded as relaying operations between the SCF and the SRF. The EstablishTemporaryConnection operation is used to set up a temporary connection to another node in the network (e.g. an external IP, which provides SRF-type services). With such a connection there is direct communication between the SCF and the external IP, with the SSF being involved only in setting up and taking down the connection. There is no relaying involving the SSF. • Call billing operations (can be used with 1-stage or 2-stage call setup): FurnishChargingInformation
  20. 20. Section 1: World Trade IN NIS 94-80nn Introduction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 6 13 December 1996 • Timer control operations (can be used with 1-stage or 2-stage call setup): ResetTimer The SCF can use the ResetTimer operation to prevent the SSF timing out a call during user interaction. • Call-independent operations: ActivateServiceFiltering ServiceFilteringResponse • Call clearing (call cannot be completed): ReleaseCall This interworking specification describes how the sending and receiving of operations relates to the sending and receiving of ETSI ISUP messages. For detailed operation descriptions, see the separate specification DMS Implementation of CS-1R INAP (ETSI Core INAP Subset) (NIS 94-8008). 1.2.2 BCSM Support 1.2.2.1 Overview of the BCSM The BCSM defined in Q.1214 provides a standard abstract view of how the processing of a basic call proceeds and the way in which basic call processing interacts with IN query processing. Q.1214 defines two BCSM entities: • The Originating BCSM (O_BCSM) • The Terminating BCSM (T_BCSM) The DMS SSP supports only the Originating BCSM. The BCSM defines the progress of a call in terms of the following: • Points In Call (PICs), which are equivalent to states. • Transitions between PICs, which correspond to state changes and indicate the possible flow of call processing from one PIC to another. • Events, which are associated with Transitions, and cause them to take place. • Detection Points (DPs), which provide IN entry points, i.e. points in the BCSM at which the SCF can become involved in order to provide an IN service. DPs are located between PICs, i.e. interaction with the IN takes place not within PICs but during transitions between them.
  21. 21. NIS 94-80nn World Trade IN Section 1: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Introduction 13 December 1996 Page 7 Sections 1.2.2.2 to 1.2.2.4 discuss DPs in more detail. 1.2.2.2 Detection Point Types DPs are intermediate points between BCSM PICs, at which there may be interaction between call processing and the IN (specifically, interaction with the SCF via the SSF). Ten DPs are defined for the O_BCSM. A given DP can be set up in any of four ways, as shown in Table 1. TDPs may be defined as conditional or non-conditional. A non-conditional TDP has no associated trigger criteria, and all calls that encounter the TDP trigger IN interaction (if the trigger is armed). A conditional TDP has one or more associated trigger criteria, and calls that encounter the TDP trigger IN interaction only if the criteria match. Table 1: DP types defined in Q.1214 TDP-R (Trigger Detection Point - Response) A trigger detection point causes interaction to take place between call processing and the SCF when static datafill-defined criteria are met. The response suffix means that information is required from the SCF as a result of the interaction, and BCSM call processing is suspended awaiting this response. TDP-N (Trigger Detection Point - Notification) A trigger detection point causes interaction to take place between call processing and the IN when static datafill-defined criteria are met. The notification suffix means that the SCF is simply told of what has happened; no information is expected from it, and BCSM call processing continues. EDP-R (Event Detection Point - Response) An event detection point is set up for a particular call in response to a request from the SCF, asking to be notified when a given call processing event takes place. The response suffix means that information is required from the SCF as a result of the interaction, and BCSM call processing is suspended awaiting this response. EDP-N (Event Detection Point - Notification) An event detection point is set up for a particular call in response to a request from the SCF, asking to be notified when a given call processing event takes place. The notification suffix means that the SCF is simply told of what has happened; no information is expected from it, and BCSM call processing continues.
  22. 22. Section 1: World Trade IN NIS 94-80nn Introduction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 8 13 December 1996 1.2.2.3 DMS SSP Support for TDPs The DMS SSP supports the following DPs as TDP-Rs: • DP-2 in the O_BCSM (Collected_Info). TDP-2 is supported both as an unconditional TDP (i.e. a call always triggers at TDP-2 if it is armed), and as a conditional TDP with either of the following trigger criteria: - Feature Code. A feature code is a string of dialled digits consisting of the character * or # followed by up to three digits. Feature codes are typically used for such things as special feature activation/deactivation. A call triggers at TDP-2 if the TDP is armed and the collected digits match a datafilled feature code. - Specific Digit String. A call triggers at TDP-2 if the TDP is armed and the first N collected digits match a datafilled digit string. • DP-3 in the O_BCSM (Analyzed_Info). TDP-3 is supported only as a conditional TDP with the Specific Called Party Number String criterion. A call triggers at TDP-3 if the TDP is armed and the first N digits of the translated called party number (up to and including the whole number) matches a datafilled number string. When a TDP is triggereD, it causes the SSF to send an InitialDP operation to the SCF to initiate IN interaction. 1.2.2.4 DMS SSP Support for EDPs DPs are dynamically armed as EDPs in response to a request from the SCF, made via an RequestReportBCSMEvent (RRBE) operation specifying one of two monitoring modes: • NotifyAndContinue, which causes the DP to be armed as an EDP-N. • Interrupted, which causes the DP to be armed as an EDP-R. An RRBE operation can specify a third mode, Transparent, which has the effect of disarming previously armed EDPs. The DMS SSP supports only one EDP on outgoing ETSI ISUP trunks. This is EDP-4, Route_Select_Failure, which can be armed as an EDP-R.
  23. 23. NIS 94-80nn World Trade IN Section 1: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Introduction 13 December 1996 Page 9 1.3 DMS SSP Support for ETSI ISUP The ISDN User Part (ISUP) is the CCS7 user part that supports not only basic telephony, but also ISDN data calls, and a range of supplementary services based on the exchange of information using out-of-band messages. ISUP performs the functions of OSI Layers 4 to 7, but in fact operates as a single layer, i.e. no information is added or removed for the intermediate layers, and ISUP information has exactly the same format at Level 7 as at Level 4. It uses the Message Transfer Part (MTP) to support message transfer, i.e. ISUP messages are conveyed between nodes in MTP Message Signal Units (MSUs). ETSI ISUP [requires a description of what ETSI ISUP actually is]. The ETSI ISUP interface supported by DMS-100E switch is fully documented in: ETSI ISUP Interface Specification Issue Aut 1.2 14 March 1991 NIS D313-1 [This references needs to be amended to show an ETSI ISUP reference.] This is a set of documents describing the ISDN User Part (ISUP), the Transaction Capabilities Application Part (TCAP), the Signalling Connection Control Part (SCCP), the Message Transfer Part (MTP), and ETSI ISUP network services. 1.4 Overview of ETSI ISUP / INAP Interworking There are two cases to consider: • After the SSF has recognised that a call requires IN processing, IN interaction is directly controlled by the SCF. This is the normal case, and is described in Section 1.4.1. • The SCF delegates IN processing to the SSF (service filtering). IN interaction is handled primarily by the SSF, which periodically reports results to the SCF. This case is described in Section 1.4.2.
  24. 24. Section 1: World Trade IN NIS 94-80nn Introduction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 10 13 December 1996 1.4.1 IN Interaction Involving the SCF The aim of IN interaction directly controlled by the SCF is usually the completion of a call (e.g. to a FreePhone or Primary Rate number). There are three stages in the processing of a call that encounters such IN interaction: • Triggering • Suspension of call processing while IN processing takes place • Resumption of call processing using information obtained from the SCF These are illustrated in Figure 3. Sections 2 to 4 of this specification are organised in accordance with this structure, as follows: • Section 2: Triggering IN Interaction on page 15, which deals with: - Triggering via ETSI ISUP signalling (note that ETSI ISUP call setup signalling is always en-bloc; ETSI ISUP does not support overlap signalling) - The impact of feature interactions before triggering • Section 3: Call Processing Suspended on page 31, which deals with: - Updating billing records with IN-related information - User interaction with the caller (to play an announcement or to collect information from the user) - Arming DPs as EDPs to monitor call completion once O_BCSM call processing resumes Note: Only EDP-4, Route_Select_Failure, is supported on outgoing DPNSS trunks. - Resumption of O_BCSM call processing • Section 4: Call Processing Resumed on page 53, which deals with: - Normal call completion after receipt of a Connect operation - Call clearing after receipt of a ReleaseCall operation Each of these sections also includes a section on error handling during the corresponding stage of an IN call.
  25. 25. NIS 94-80nn World Trade IN Section 1: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Introduction 13 December 1996 Page 11 Figure 3 Stages in the processing of an IN call SSP routes call onward, using information from SCF to modify information received via ETSI ISUP SCF sends Connect with call setup information SCF-initiated interaction with caller to collect further information; speech path through-connected backward via ETSI ISUP Charging information received from SCF (optional) Call triggers on armed TDP; IN interaction initiated and call processing suspended Collected digits are translated Incoming ETSI ISUP call received by DMS Call origination Call termination Call processing before triggering of IN interaction Call processing suspended during IN interaction Call processing resumed after IN interaction 1-stage call setup 2-stage call setup SCF sends ReleaseCall with release code Test TDP-2 to see if it is armed Test translated digits for criteria match Not armed No match TDP-2 triggers TDP-3 triggers No IN interaction SCF tells SSF to arm EDPs (note that they will be disarmed when the call is connected) Call setup with monitoring
  26. 26. Section 1: World Trade IN NIS 94-80nn Introduction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 12 13 December 1996 1.4.2 IN Interaction Handled by SSF (Service Filtering) The aim of service filtering is to count the number of calls made to a specified number, or the number of calls made to each one of a series of numbers (e.g. for TeleVoting). This counting is done by the SSF; there is no SCF involvement, except that the SCF initiates service filtering and the SSF periodically reports results to the SCF. The stages are: • Activation of service filtering • Triggering for calls to be filtered • Processing of calls that trigger service filtering • Termination of service filtering These are illustrated in Figure 4. Service filtering is described in more detail in Section 5: Service Filtering on page 61.
  27. 27. NIS 94-80nn World Trade IN Section 1: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Introduction 13 December 1996 Page 13 Figure 4 Stages in service filtering Call triggers at an armed TDP; IN interaction initiated Test TDP-2 to see if it is armed Incoming ETSI ISUP call received by DMS SSP Call origination PRI call processing before triggering Call count incremented Translate collected digits Test translated digits for criteria match TDP-2 triggers Activation of service filtering Service filtering terminates when final report sent to SCF Filtering results collected and reported SCF tells SSF to begin filtering, specifying: • Call processing information • How long filtering is to last • How often to report results • Numbers for which to provide counts of incoming calls PRI call processing continued at SSF Call cleared with specified Cause value Call billed as specified Specified announcement played to caller Final report of call counts provided when specified duration of filtering expires Interim reports of call counts provided at specified intervals Termination of service filtering Call termination TDP-3 triggers Not armed No IN interaction No match Filtered call
  28. 28. Section 1: World Trade IN NIS 94-80nn Introduction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 14 13 December 1996
  29. 29. NIS 94-80nn World Trade IN Section 2: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Triggering IN Interaction 13 December 1996 Page 15 2 Triggering IN Interaction 2.1 Introduction On receipt of an incoming ETSI ISUP call on the originating side of the DMS SSP, the SSF remains in the state Idle, while the CCF (which contains the O_BCSM) processes the call as normal (traversing through the various PICs and DPs of the O_BCSM), until and unless an armed TDP is encountered. If an armed TDP is encountered, the SSF FSM moves to the state Trigger Processing and determines whether DP criteria conditions have been met. If the TDP is armed as an unconditional TDP, or if criteria conditions are met (criteria match established) for a conditional TDP, and the TDP encountered is a TDP-R, the call triggers and the SSF will: 1. Suspend O_BCSM call processing at the current DP 2. Start the guard timer TSSF 3. Generate an INAP InitialDP operation and send it to the SCF 4. Move to the state Waiting For Instructions If criteria conditions are not met (criteria match not established), e.g. because the call is not an IN call, the SSF FSM returns to the state Idle and O_BCSM call processing continues with no IN interaction.
  30. 30. Section 2: World Trade IN NIS 94-80nn Triggering IN Interaction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 16 13 December 1996 2.2 IN Interaction with ETSI ISUP En-Bloc Signalling 2.2.1 Overview of En-Bloc Signalling In the case of en-bloc signalling, the IAM message from the originating side contains complete called party information. The ETSI ISUP/INAP interaction is as shown in Figure 5. Figure 5 Incoming ETSI ISUP call (successful trigger) IAM DMS SSP SCP InitialDP Start TSSF Originating side BCSM TDP-2 armed? Waiting for Instructions SSF FSM Criteria match PIC_1 PIC_2 Collect digits PIC_3 Translate digits TDP-3 armed? Idle Trigger Processing Trigger Processing IdleCall proceeds with no IN interaction PIC_4 Criteria match No match No match
  31. 31. NIS 94-80nn World Trade IN Section 2: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Triggering IN Interaction 13 December 1996 Page 17 2.2.2 Sequence of Events The sequence of events is as follows: 1. A call arrives at the DMS SSP. See Section 2.2.2.1. 2. The DMS SSP collects digits from the caller (see Section 2.2.2.2), and possibly triggers interaction between the O_BCSM and the SSF (see Section 2.2.2.3). 3. The DMS SSP translates the collected digits (see Section 2.2.2.4), and possibly triggers interaction between the O_BCSM and the SSF (see Section 2.2.2.5). 4. If the call has not triggered at this point, it completes without any IN interaction. Trigger processing is described in Section 2.2.2.6. Trigger processing may initiate IN interaction, as described in Section 2.2.2.7. 2.2.2.1 Call Arrival (PIC_1) When the DMS SSP receives a ETSI ISUP Initial Address Message (IAM), it creates a new instance of the ETSI ISUP Originating Basic Call State Machine (O_BCSM), which will initially be in PIC_1. The call is marked as a potential IN call according to the trigger subscription(s) in effect at the switch. Two types of subscription are supported: • Office or switch-wide subscription, which means that all incoming ETSI ISUP calls are treated as potential IN calls. • Trunk group subscription, which means that only ETSI ISUP calls incoming on specified trunk groups are treated as potential IN calls. Trunk group subscription takes priority over office subscription. No significant processing takes place within PIC_1, so the O_BCSM moves from PIC_1 to PIC_2. The DMS SSP does not support the arming of TDP-1 (Originating Attempt Authorised), so this TDP cannot trigger interaction with the SSF. The SSF FSM (with which no interaction has yet taken place) is in state Idle.
  32. 32. Section 2: World Trade IN NIS 94-80nn Triggering IN Interaction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 18 13 December 1996 2.2.2.2 Digit Collection (PIC_2) In PIC_2, the DMS SSP collects dialled digits, which are provided in the Address Signals parameter of the IAM message. The O_BCSM leaves PIC_2. The SSF FSM remains in state Idle. 2.2.2.3 Triggering at TDP-2 (Collected Info) On leaving PIC_2, the O_BCSM encounters TDP-2 (Collected Info). This can be armed as a TDP-R, either unconditionally or with the following trigger criteria: • Feature Code • Specific Digit String Note: TDP-2 is armed unconditionally by datafilling a value of 0 for Minimum Digits. If Minimum Digits is datafilled with a value n (n>0), the call will trigger only if the number of dialled digits is greater than or equal to n. If the call is marked as a potential IN call, and TDP-2 is armed, this initiates interaction between the O_BCSM and the SSF. The SSF FSM moves from state Idle to state Trigger Processing. See Section 2.2.2.6 for a description of what happens in this state. Otherwise, the O_BCSM moves from PIC_2 to PIC_3 without initiating interaction with the SSF. The SSF FSM remains in state Idle. 2.2.2.4 Digit Translation (PIC_3) In PIC_3 the digits received from the originating side go through translations. After translations, the O_BCSM leaves PIC_3. The SSF FSM remains in state Idle. 2.2.2.5 Triggering at TDP-3 (Analysed Info) On leaving PIC_3, the O_BCSM encounters TDP-3 (Analyzed Info). This can be armed as a TDP-R, with trigger criterion Specific Called Party Number String. If the call is marked as a potential IN call, and TDP-3 is armed, this initiates interaction between the O_BCSM and the SSF. The SSF FSM moves from state Idle to state Trigger Processing. See Section 2.2.2.6 for a description of what happens in this state.
  33. 33. NIS 94-80nn World Trade IN Section 2: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Triggering IN Interaction 13 December 1996 Page 19 Otherwise, the O_BCSM moves from PIC_3 to PIC_4 without initiating interaction with the SSF, and the SSF FSM remains in state Idle. Since the DMS SSP supports no TDPs after TDP-3, the call will now progress to completion without any IN interaction. 2.2.2.6 Trigger Processing An armed TDP will only initiate IN processing if the trigger criterion associated with the TDP matches one of the datafilled values at the switch. If a TDP has triggered, the SSF tests whether trigger criteria match a value datafilled at the switch: • If TDP-2 is armed with Minimum Digits as the trigger criterion, is the number of dialled digits greater than or equal to the datafilled value? Note: If Minimum Digits is datafilled with the value 0, the call will always initiate IN processing. The TDP is an unconditional TDP. • If TDP-2 is armed with Feature Code as the trigger criterion, do the collected digits match a datafilled feature code for an IN service? • If TDP-2 is armed with Specific Digit String as the trigger criterion, do the collected digits match a datafilled digit string associated with an IN service? • If TDP-3 is armed with Specific Called Party Number String as the trigger criterion, do the translated collected digits match a datafilled called party number associated with an IN service? If there is no criteria match, the call is not recognised as an IN call, and the SSF FSM moves from state Trigger Processing back to state Idle. The O_BCSM moves to PIC_3 (see Section 2.2.2.4) or to PIC_4 (in which case the call progresses to completion without any IN interaction), depending on which TDP has triggered. If there is a criteria match, the call is recognised as an IN call. O_BCSM processing is suspended and the SSF initiates IN interaction as described in Section 2.2.2.7. Note: If IAM does not include a Calling Party Number parameter, and the service key indicates that CLI is required, the call will be cleared.
  34. 34. Section 2: World Trade IN NIS 94-80nn Triggering IN Interaction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 20 13 December 1996 2.2.2.7 Initiating IN Interaction The SSF initiates IN interaction by assembling an INAP InitialDP operation and sending this to the SCF in a TCAP BEGIN package. The parameters of the InitialDP operation are assembled partly from ETSI ISUP message parameters, and partly from triggering information datafilled at the switch, as follows: For a more detailed description of IAM / InitialDP parameter mapping, refer to Appendix A. When the SSF has sent InitialDP, the SSF FSM moves from state Trigger Processing to state Waiting For Instructions, and waits for a response from the SCF. Call processing in the O_BCSM remains suspended. See Chapter 3 for a description of the interaction between ETSI ISUP and INAP while call processing is suspended. a.If datafill does not explicitly request that Calling Party Number be included in Ini- tialDP, it is not included, even if it is provided in IAM. ETSI ISUP IAM parameter INAP InitialDP parameter Calling Party’s Category (in IAM Message Indicators) CallingPartysCategory Called Party Number CalledPartyNumber Calling Party Numbera CallingPartyNumber <datafill for dialled digits> ServiceKey Supplied by DMS SSP EventTypeBCSM Transmission Medium Requirement bearerCapability
  35. 35. NIS 94-80nn World Trade IN Section 2: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Triggering IN Interaction 13 December 1996 Page 21 2.3 IN Interaction with ETSI ISUP Overlap Signalling Handling of incoming ETSI ISUP overlap calls is similar to that of ETSI ISUP en-bloc calls. The primary differences are: • The initial IAM message does not contain all the information necessary to complete the call. • Triggering may occur before all called party digits have been received. This results in more complex interaction, which is summarised in Section 2.3.1 and described in detail in Section 2.3.2. 2.3.1 Overview The ETSI ISUP/INAP interaction is as shown in Figure 6. 2.3.2 Sequence of Events The sequence of events is as follows: 1. A call arrives at the DMS SSP. See Section 2.3.2.1. 2. The DMS SSP collects digits from the caller (see Section 2.3.2.2), and possibly triggers interaction between the O_BCSM and the SSF (see Section 2.3.2.3). 3. The DMS SSP translates the collected digits (and may collect more digits) (see Section 2.3.2.4), and possibly triggers interaction between the O_BCSM and the SSF (see Section 2.3.2.5). 4. If the call has not triggered at this point, it completes without any IN interaction. Trigger processing is described in Section 2.3.2.6. Trigger processing may initiate IN interaction, as described in Section 2.3.2.7.
  36. 36. Section 2: World Trade IN NIS 94-80nn Triggering IN Interaction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 22 13 December 1996 Figure 6 Incoming ETSI ISUP overlap call (successful trigger) 2.3.2.1 Call Arrival (PIC_1) When the DMS SSP receives an ETSI ISUP Initial Address Message (IAM), it creates a new instance of the ETSI ISUP Originating Basic Call State Machine (O_BCSM), which will initially be in PIC_1. The call is marked as a potential IN call according to the trigger subscription(s) in effect at the switch. Two types of subscription are supported: • Office or switch-wide subscription, which means that all incoming ETSI ISUP calls are treated as potential IN calls. IAM DMS SSP SCP SAM(s) Originating side TDP-2 armed? BCSM SSF FSM PIC_2 Collect digits PIC_1 Idle Trigger Processing Waiting for Instructions No match PIC_3 Translate digits TDP-3 armed? Trigger Processing Call proceeds with no IN interaction PIC_4 Idle No match Criteria match (additional info not req’d) InitialDP Start TSSF Potential match Potential match Start inter-digit timer
  37. 37. NIS 94-80nn World Trade IN Section 2: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Triggering IN Interaction 13 December 1996 Page 23 • Trunk group subscription, which means that only ETSI ISUP calls incoming on specified trunk groups are treated as potential IN calls. Trunk group subscription takes priority over office subscription. No significant processing takes place within PIC_1, so the O_BCSM moves from PIC_1 to PIC-2. The SSF FSM (with which no interaction has yet taken place) is in state Idle. The DMS SSP does not support the arming of TDP-1 (Originating Attempt Authorised), so this TDP cannot trigger interaction with the SSF. The SSF FSM (with which no interaction has yet taken place) is in state Idle. 2.3.2.2 Digit Collection (PIC_2) In PIC_2, the DMS SSP collects dialled digits, which are provided in the Address Signals parameter of the IAM message. The O_BCSM leaves PIC_2, even though digit collection is still in progress. The SSF FSM remains in state Idle. The procedure for collecting further digits is described below. Although it is described here for convenience, it should be understood that the O_BCSM will have moved out of PIC_2 by the time further digits arrive. After receiving the IAM message, the DMS SSP starts an inter-digit timer. The originating side will provide further digits in one or more SAM messages. Each time a SAM message is received, the inter-digit timer is restarted. Digit collection is complete when the DMS SSP receives a SAM message with an end of digits indicator from the originating side, or when the inter-digit timer expires. If the inter-digit timer expires without a complete number having been received, the call is cleared. 2.3.2.3 Triggering at TDP-2 (Collected Info) On leaving PIC_2, the O_BCSM encounters TDP-2 (Collected Info). This can be armed as a TDP-R, either unconditionally or with the Specific Digit String trigger criteria. TDP-2 is armed unconditionally by datafilling a value of 0 for Minimum Digits. If Minimum Digits is datafilled with the value n (>0), TDP-2 is triggered only when at least n digits have been collected from the originating side. Note: If the DMS SSP receives an indication that sending is complete (e.g. receipt of a SAM message with an end of digits indicator) before it has received the specified minimum number of digits for triggering, the call will not trigger.
  38. 38. Section 2: World Trade IN NIS 94-80nn Triggering IN Interaction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 24 13 December 1996 If the call is marked as a potential IN call, and TDP-2 is armed, this initiates interaction between the O_BCSM and the SSF. The SSF FSM moves from state Idle to state Trigger Processing. See Section 2.3.2.6 for a description of what happens in this state. Otherwise, the O_BCSM moves from PIC_2 to PIC_3 without initiating interaction with the SSF. The SSF FSM remains in state Idle. 2.3.2.4 Digit Translation (PIC_3) In PIC_3 the digits received from the originating side go through translations. The number that is translated consists of whatever digits have been collected so far in IAM and SAM messages. When translations produce a routing address, the O_BCSM leaves PIC_3. Note: This condition may be satisfied before digit collection is complete, so digit collection may continue after the O_BCSM leaves PIC_3. The SSF FSM remains in state Idle. 2.3.2.5 Triggering at TDP-3 (Analyzed Info) On leaving PIC_3, the O_BCSM encounters TDP-3 (Analyzed Info). This can be armed as a TDP-R, with trigger criterion Specific Called Party Number String. If the call is marked as a potential IN call, and TDP-3 is armed, this initiates interaction between the O_BCSM and the SSF. The SSF FSM moves from state Idle to state Trigger Processing. See Section 2.3.2.6 for a description of what happens in this state. Otherwise, once all digits have been collected and translated, the O_BCSM moves from PIC_3 to PIC_4 without initiating interaction with the SSF. The SSF FSM remains in state Idle. Since the DMS SSP supports no TDPs after TDP-3, the call will now progress to completion without any IN interaction.
  39. 39. NIS 94-80nn World Trade IN Section 2: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Triggering IN Interaction 13 December 1996 Page 25 2.3.2.6 Trigger Processing The interactions between overlap signalling and trigger processing are illustrated in Figure 7. Figure 7 Interactions Between Overlap Signalling and Trigger Processing An armed TDP will only initiate IN processing if both of the following conditions are true: • The trigger criterion associated with the TDP matches one of the datafilled values at the switch. See Establishing a Criteria Match. Call triggers at an armed TDP Is it a conditional TDP? Is there a criteria match? Is digit collection complete? Can we send InitialDP with partial CdPN? Send InitialDP Go to state WFI Start TSSF No Yes Go to next PIC Go to state Idle NoYes Wait for next SAM message or inter-digit timeout No Potential* Wait for next SAM message or inter-digit timeout * A potential criteria match exists when digit collection is still in progress and collected digits may provide a criteria match when combined with digits still to be collected. Wait for next SAM message or inter-digit timeout Have we collected the minimum number of digits required? Yes No No Yes Yes Continue digit collection if InitialDP sent with partial CdPN Is digit collection complete? No Yes
  40. 40. Section 2: World Trade IN NIS 94-80nn Triggering IN Interaction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 26 13 December 1996 • The DMS SSP has received sufficient information to initiate IN interaction. The datafilled service key for a service will indicate what information the SSF requires before it can send InitialDP: - Does InitialDP require a complete called party number, or can it be sent with a partial called party number? - If InitialDP can be sent with a partial called party number, have the minimum number of digits been collected (as specified by the datafilled value for Minimum Digits)? See Determining When to Send InitialDP. Establishing a Criteria Match If a conditional TDP has triggered, the SSF tests whether the associated trigger criterion matches any of the values datafilled at the switch: • If TDP-2 is armed with Specific Digit String as the trigger criterion, do the collected digits match a datafilled digit string associated with an IN service? • If TDP-3 is armed with Specific Called Party Number String as the trigger criterion, do the translated digits collected so far match a datafilled called party number associated with an IN service? A test for a match may yield any of three results: • No match is possible. Either digit collection has completed without producing a match, or enough digits have already been collected to rule out the possibility of a match. For example, 1234 has been collected, and all the datafilled criteria for Specific Called Party Number String begin with 1233. The O_BCSM moves to the next PIC. The SSF FSM moves to state Idle. • A match has been found. The SSF now determines if it has enough information to initiate IN interaction (see Determining When to Send InitialDP). Note: There may be cases when collected digits match one of the datafilled criteria, but further digits may produce a different match. For example, 1234 has been collected, and the datafilled criteria for Specific Called Party Number String include both 1234 (an actual match) and 12345 (a potential match). In such ambiguous cases, the SSF will wait for further digits and check again for a match. • There is a potential match. Although no actual match has been found, digit collection is still in progress and may produce digits which, when combined with digits already collected, produce a match. For example, 123 has been
  41. 41. NIS 94-80nn World Trade IN Section 2: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Triggering IN Interaction 13 December 1996 Page 27 collected, and the datafilled criteria for Specific Called Party Number String includes 1234. The O_BCSM remains suspended at the current TDP, and the SSF FSM remains in state Trigger Processing. As each SAM message arrives with more digits, the SSF repeats the test for a criteria match, incorporating the newly received digits. (Note: The newly received digits go through translations before the SSF tests for a criteria match.) This process continues until either the SSF determines that a match definitely does or does not exist (in which case the appropriate action is taken, as described above), or until digit collection completes without producing a match (in which case the O_BCSM moves to the next PIC, and the SSF FSM moves to state Idle). If an unconditional TDP has triggered, there are no trigger criteria to be matched. The SSF only needs to consider whether it has enough information to initiate IN interaction (see Determining When to Send InitialDP). Determining When to Send InitialDP Once the SSF has determined that it should initiate IN interaction (for an unconditional TDP, or for a conditional TDP for which a criteria match has been found), it must determine whether enough information has been provided to start the interaction (i.e. by sending InitialDP to the SCF). The service key associated with the IN service with which the call is matched will indicate whether InitialDP can be sent with a full or partial called party number. If InitialDP can be sent with a partial called party number, the datafilled value for Minimum Digits will specify the minimum number of digits that must be collected before InitialDP can be sent. There are two possibilities: • No further information is required. • Addtional called party digits are required. Note: If the service key indicates that CLI is required and the CLI was not included in the initial IAM message, the call will be cleared. There are no facilities for requesting CLI from the originating side.
  42. 42. Section 2: World Trade IN NIS 94-80nn Triggering IN Interaction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 28 13 December 1996 No Further Information Required No further information is required in the following cases: • InitialDP can be sent with a partial called party number (or, if it requires a complete called party number, it has been collected and digit collection is complete). • The minimum number of digits have been collected. O_BCSM processing is suspended and the SSF initiates IN interaction, as described in Section 2.3.2.7. The DMS SSP can continue to collect Address Signals while IN call processing takes place. Addtional Called Party Digits Required Additional called party digits (only) are required in the following cases: • The service key indicates that a complete called party number is required, and digit collection is still in progress. • The number of digits collected so far is less than the datafilled value of Minimum Digits. The DMS SSP will collect additional digits, received in SAM messages, until: • A SAM message is received with an end of digits indicator, indicating that a complete called party number has been received. • The number of digits collected exceeds the datafilled value for Minimum Digits. • The inter-digit timer expires. In the first two cases, the DMS SSP suspends O_BCSM processing and the SSF initiates IN interaction, as described in Section 2.3.2.7. If the inter-digit timer expires before sufficient digits have been collected, the call will be cleared. Note: If digit collection is completed before the required minimum number of digits has been collected, the call will not trigger. The SSF will move to the next PIC, and the SSF FSM will move to state Idle.
  43. 43. NIS 94-80nn World Trade IN Section 2: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Triggering IN Interaction 13 December 1996 Page 29 2.3.2.7 Initiating IN Interaction The SSF initiates IN call processing by assembling an INAP InitialDP operation and sending this to the SCF in a TCAP BEGIN package. The parameters of the InitialDP operation are assembled partly from ETSI ISUP message parameters, and partly from triggering information datafilled at the switch, as follows: For a more detailed description of IAM / InitialDP parameter mapping, refer to Appendix A. Having sent the InitialDP, the SSF FSM moves from state Trigger Processing to state Waiting For Instructions, and waits for a response from the SCF. Call processing in the O_BCSM remains suspended. See Chapter 3 for a description of the interaction between ETSI ISUP and INAP while call processing is suspended. 2.4 Feature interaction Before First IN trigger If the incoming call has been routed via a switch-based Virtual Private Network (VPN) and authorisation checks have already been carried out on the caller, this may have an impact on the way in which the call interacts with IN. Such possible impacts are currently being investigated, and will be documented in a future issue of this specification. a.If datafill does not explicitly request that CLI be included in InitialDP, it is not in- cluded, even if it is provided in IAM. ETSI ISUP parameter INAP InitialDP parameter IAM Message Indicators (Calling Party Category) CallingPartysCategory Called Address CalledPartyNumber Line Identitya (from IAM) CallingPartyNumber <datafill for dialled digits> ServiceKey Supplied by DMS SSP EventTypeBCSM Transmission Medium Requirement bearerCapability
  44. 44. Section 2: World Trade IN NIS 94-80nn Triggering IN Interaction Release 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 30 13 December 1996 2.5 Error handling 2.5.1 Errors Detected by INAP No errors are detected by INAP during this stage of call processing. Detection of errors arising from sending of InitialDP is covered in Section 3, as they are reported to the SSF while call processing is suspended. 2.5.2 Timer Expiry Expiry of TSSF after InitialDP is sent is covered in Section 3, as it occurs while call processing is suspended. 2.5.3 Errors Detected by TCAP No errors are detected by TCAP during this stage of call processing. Detection of errors arising from sending of InitialDP is covered in Section 3, as they are reported to the SSF while call processing is suspended. 2.5.4 Errors Detected by ETSI ISUP ETSI ISUP errors that occur before IN triggering takes place are handled by standard ETSI ISUP mechanisms (e.g. call clearing). There is no ETSI ISUP/INAP interaction.
  45. 45. NIS 94-80nn World Trade IN Section 3: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Call Processing 13 December 1996 Page 31 3 Call Processing Suspended 3.1 Overview When there has been a criteria match at an armed TDP-R in the O_BCSM, O_BCSM call processing is suspended to allow IN interaction to take place under the control of the SCF. During O_BCSM call suspension, while there is an SSF/SCF control relationship, the SCF can interact with the SSF in the following ways: • Update billing records with IN-related information • Initiate and control user interaction with the caller by playing an announcement and/or collecting information from the user • Reset the timer used by the SSF to control how long it will wait for a response from the SCF • Resume O_BCSM call processing, having provided a complete or partial replacement for the original called party number • Clear the call Note: The SSF may initiate call monitoring by arming EDPs, or request the SSF to provide information about call completion. However, ETSI ISUP does not support these features. When the call is connected, any armed EDPs will be disarmed and default values for will not be provided for any requested call information.
  46. 46. Section 3: World Trade IN NIS 94-80nn Call Processing SuspendedRelease 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 32 13 December 1996 3.2 Billing For non-IN calls, the DMS SSP generates a billing record for a call after the call has been through translations, unless translations indicate that no billing record is to be generated. If a call triggers at TDP-3, therefore, a billing record may or may not already exist for the call. If the SCF sends FCI operations containing billing information, this information is added to the existing billing record, or a billing record is created if one does not already exist. If a call triggers at TDP-2, the call has not yet been through translations, so no billing record exists for the call. If the SCF sends FCI operations containing billing information, a billing record will be created for the call. In this case, the DMS SSP will be prevented from creating another billing record when the call goes through translations. See Section 3.2.1 for more information about billing records. 3.2.1 AMA Billing Records The DMS SSP supports Automated Message Accounting (AMA) for billing, and updates fields in AMA records using a combination of FCI parameter values and information datafilled against the trigger criteria for a service (specifically, the Called Party Number and Calling Party Number, as used to provide values for the InitialDP operation). AMA modules are used as follows: • In the base AMA record for an IN call, the fields Terminating Open Digits 1 and Terminating Open Digits 2 (normally used to store translated called party number digits) are filled with hexadecimal Fs (1111). These will eventually be overwritten with the final called party number, as modified/provided by Connect. • Appended to the base record may be either a Type 40 (Digits) module or a Type 28 (Additional Digits Dialled) module, as specified by datafilled service data. The Type 40 module uses its Dialled Digits 1 and Dialled Digits 2 fields to record the translated dialled digits available when the InitialDP operation is sent for the call (i.e. the same digits conveyed in the CalledPartyNumber parameter of InitialDP). The Type 28 module uses its Additional Digits Dialled field to record additional authorisation and PIN digits dialled by a VPN user.
  47. 47. NIS 94-80nn World Trade IN Section 3: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Call Processing 13 December 1996 Page 33 • The SCF can send an FCI operation to instruct the DMS SSP to append an AMA Type 199 module to the base record. This module type contains operator-defined data. This allows network operators great flexibility in determining what billing information they wish to record, particularly since successive FCI operations can be used to append a number of Type 199 modules to the base record. The processing of the billing information provided by the SCF is handled entirely within the SSF, and requires no interaction with ETSI ISUP. For a more detailed description of AMA billing for IN calls, see AG4629 (TDP-3 billing) and AG5150 (TDP-2 billing). 3.3 User Interaction The SCF can initiate, control and terminate direct in-band interaction with the calling party by means of INAP operations. Such interaction might, for example, involve the calling party dialling digits (e.g. a PIN for authorisation) in response to an announcement, if the InitialDP operation does not provide the SCF with enough information to screen and route a call. User interaction can be handled in either of two ways: • By the DMS SSP’s integrated IP/SRF. This is described in Section 3.3.2. • By an external IP/SRF. This is described in Section 3.3.3. Both types of IP can be used for user interaction within the same call, although only one type of IP can be in use at any given moment; that is, if a call is connected to one type of IP, that connection must be closed before the call can be connected to the other type of IP. 3.3.1 INAP Operations Used The following operations are concerned with establishing a connection between the SCF and the provider of SRF-type services: • ConnectToResource (CTR) EstablishTemporaryConnection (ETC) Sent from the SCF to the SSF to tell it to set up a connection to a specialised resource, typically so that it can provide instructions to the calling party or obtain additional information.
  48. 48. Section 3: World Trade IN NIS 94-80nn Call Processing SuspendedRelease 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 34 13 December 1996 The DMS SSP supports the CTR operation for connections to the integrated DMS IP, i.e. to MTM EDRAM announcements or DTC tone generation and detection. In this scenario, the SSF then relays SCF-to-SRF operations to the integrated IP. The DMS SSP supports the ETC operation for connections to an external IP. The DMS SSP sets up a link to the external IP over a PRI trunk. Once the connection is fully established (see the description of the AssistRequestInstructions operation below), operations are exchanged directly between the SCF and the external IP, with no further involvement from the SSF. • AssistRequestInstructions (ARI) Sent from the SRF to the SCF to complete the connection between the SCF and an external IP. Note: The ARI operation does not involve any SSF interaction. The following INAP operations apply to both types of IP connection. The only difference is that for an integrated IP connection they will be sent to the SSF, which relays them to an internal SRF. For an external IP connection, operations are exchanged directly between the SCF and the external IP: • PlayAnnouncement (PA) Sent from the SCF to the SRF after a user-SRF connection has been established under SCF control, to tell the SRF to provide a specified tone or announcement in-band. There is no input from the user. • SpecializedResourceReport (SRR) Sent from the SRF to the SCF to confirm that a specified tone or announcement has been provided in-band via a PA operation. • PromptAndCollectUserInformation (P&C) Sent from the SCF to the SRF after a user-SRF connection has been established under SCF control, to tell the SRF to provide a specified tone or announcement in-band and to collect information (e.g. digits in-band) from the user. The collected information is sent to the SCF via the TCAP Return Result defined for the P&C operation.
  49. 49. NIS 94-80nn World Trade IN Section 3: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Call Processing 13 December 1996 Page 35 The following INAP operation is concerned with the timer that the DMS SSP uses to control how long it will wait for a response from the SCP or an external IP before timing out: • ResetTimer (RT) Sent from the SCF to the SSF to tell it to restart the TSSF timer with a specified period. This allows the SCF to prevent the SSF from timing out a call in cases where IN processing takes longer than usual (e.g. while waiting for a response from an external IP, or while executing complex service logic). Note: Use of the ResetTimer operation is not restricted to user interaction. The SCF can send ResetTimer to the SSF at any point during an SSF/SCF control relationship. The following INAP operation is concerned with terminating the connection between the SCF and the SRF, and applies to both integrated and external IPs: • DisconnectForwardConnection (DFC) Sent from the SCF to the SSF to tell the SSF to disconnect the forward SRF connection for a call. This indicates that no further interaction with the user is required for the moment, but the SCF/SSF connection remains in place. Note: In the case of a connection to an external IP, the SRF can initiate disconnection (see Section 3.3.3.2). 3.3.2 User Interaction Using an Integrated IP This section describes user interaction using the DMS SSP’s integrated IP. 3.3.2.1 Message Flow Overview User interaction requires the presence of a speech path for in-band communication with the caller (voice prompts, network tones, DTMF digits and so on). In a call without user interaction, the speech path would be set up in response to an ANS message from the terminating side. If user interaction is required before the call is routed to the terminating side (i.e. before the SCF issues Connect), the DMS SSP must set up the speech path at an earlier stage in the progress of the call.
  50. 50. Section 3: World Trade IN NIS 94-80nn Call Processing SuspendedRelease 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 36 13 December 1996 To set up the speech path, the DMS SSP generates the following ETSI ISUP messages and sends them to the originating side: 1. ACM. This tells the caller to stop sending digits. The DMS SSP usually sends ACM when it has determined that it has received a complete called party number. If this has already happened by the time user interaction is requested, ACM will already have been sent, so it isn’t necessary to send it again. 2. ANS. This causes the speech path to be set up. These messages are referred to as “early” setup messages, because they cause the speech path to be set up earlier than would be the case if it was set up in response to ETSI ISUP messages received from the terminating side after the call is routed. Note: If Malicious call trace is in progress, the sending of early setup messages will break the trace. No early setup messages are sent if a speech path has already been set up. This will be the case if: • There has already been user interaction earlier in the call. • The call has tried unsuccessfully to connect (ACM, but not ANS, has been received from the terminating side). When the call is finally routed, the terminating side will eventually return the following ETSI ISUP messages to the DMS SSP: ACM ANS These are the messages that would normally cause the speech path to be set up to the caller. However, since the speech path has already been set up to handle user interaction, these messages do not need to be relayed to the originating side, so they are simply discarded by the DMS SSP. The ETSI ISUP/INAP interaction is as shown in Figure 8.
  51. 51. NIS 94-80nn World Trade IN Section 3: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Call Processing 13 December 1996 Page 37 Figure 8 ETSI ISUP call with IN user interaction (integrated IP) DMS SSP SCP state c Waiting for Instructions BCSM SSF FSMSSRM state 1 Idle state 2 Connected state d Waiting for End of User Interaction To state 1 Idle To state c Waiting for Instructions ACM ANM CTR SRR or PA or P&C DFC PA or P&C state 2 Connected state d Waiting for End of User Interaction Any subsequent ConnectToResource does not require ETSI ISUP interaction, as speech path is already through-connected state 3 User Interaction ETSI ISUP ACM (if not already sent) and ANM sent to open speech path prior to user interaction In-band user interaction tone/announcement digits (RR) tone/announcement P&C(RR) Originating side RT RT RT O_BCSM remains suspended throughout Optional further CTR
  52. 52. Section 3: World Trade IN NIS 94-80nn Call Processing SuspendedRelease 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 38 13 December 1996 3.3.2.2 Sequence of Events The sequence of events for user interaction via an integrated IP is as follows: 1. Before receiving an INAP CTR operation: - The SSF FSM is in state Waiting For Instructions - O_BCSM call processing is suspended - The SSRM (with which no interaction has yet taken place) is in state Idle. 2. When the SSF receives an INAP CTR operation from the SCF, the following call processing actions occur within the DMS SSP: - The SSF FSM moves to state Waiting For End Of User Interaction. - The SSRM moves to state Connected. - If no speech path to the caller has been set up, the DMS SSP sets one up, as described in Section 3.3.2.1. 3. The calling party is now through connected to on-board DMS SSP tone and announcement capabilities (provided by the SRF/integrated IP). 4. User interaction can begin, as described in the specification DMS Implementation of CS-IR INAP (ETSI Core INAP Subset), and summarised in Figure 8. No further ETSI ISUP interaction is necessary during interaction with the user. 5. The SCF terminates user interaction by sending an INAP DFC operation to the SSF. The following call processing actions take place within the DMS SSP: - The SSRM moves to state Idle. - The SSF FSM moves to state Waiting For Instructions. The speech path to the caller remains open. Any subsequent interaction uses the speech path already set up. At any point while call processing is suspended, the SCF can send a ResetTimer operation to the SSF. The effect of ResetTimer is to restart the TSSF timer, which is used to control the amount of time for which the SSF will wait for some kind of response from the SCF (see Section 3.5.2.1 for more information about TSSF).
  53. 53. NIS 94-80nn World Trade IN Section 3: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Call Processing 13 December 1996 Page 39 Note: The SCF is allowed to send only one ResetTimer operation before sending some other kind of response to the SSF (e.g. CTR, Connect). However, after sending such a response, the SCF can send as many ResetTimer operations as it wishes. This is illustrated in Figure 8. 3.3.3 User Interaction Using an External IP This section describes user interaction using an external IP. 3.3.3.1 Message Flow Overview User interaction requires the presence of a speech path for in-band communication with the caller (voice prompts, network tones, DTMF digits and so on). In a call without user interaction, the speech path would be set up in response to an ANS message from the terminating side. If user interaction is required before the call is routed to the terminating side (i.e. before the SCF issues Connect), the DMS SSP must set up the speech path at an earlier stage in the progress of the call. See Setting Up a Speech Path. If user interaction is handled via an external IP rather than the DMS SSP’s integrated IP, the DMS SSP also needs to set up a link to the external IP and connect the caller’s speech path to this link. See Connecting to an External IP. The ETSI ISUP/INAP and PRI/INAP interactions are as shown in Figure 9. Setting Up a Speech Path To set up the speech path, the DMS SSP sends the following ETSI ISUP messages to the originating side: 1. ACM. This tells the caller to stop sending digits. The DMS SSP usually sends ACM when it has determined that it has received a complete called party number. If this has already happened by the time user interaction is requested, ACM will already have been sent, so it isn’t necessary to send it again. 2. ANS. This causes the speech path to be set up. These messages are referred to as “early” setup messages, because they cause the speech path to be set up earlier than would be the case if it was set up in response to ETSI ISUP messages received from the terminating side after the call is routed. Note: If Malicious call trace is in progress, the sending of early setup messages will break the trace.
  54. 54. Section 3: World Trade IN NIS 94-80nn Call Processing SuspendedRelease 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 40 13 December 1996 Figure 9 ETSI ISUP call with IN user interaction (external IP) DMS SSP SCP state c Waiting for Instructions BCSM SSF FSM SSRM state 1 Idle state 2 Connected To state 1 Idle To state c Waiting for Instructions ACM ANM SRR or PA or P&C DFC PA or P&C state 2 Connected Any subsequent ETC does not require ETSI ISUP interaction, as speech path is already open state 3 User Interaction ETSI ISUP ACM and ANM, or in some cases ANM only, sent to open speech path prior to user interaction, but only if not In-band user interaction tone/announcement digits (RR) tone/announcement P&C(RR) Originating side External IP ETC SETUP ALERTING/ PROGRESS CONNECT ARI DISCONNECT RELEASE COMPLETE RT RT DISCONNECT RELEASE COMPLETE O_BCSM remains suspended throughout state e Waiting For End Of Temporary Connection state e Waiting For End Of Temporary Connection Optional further CTR Disconnection initiated by external IP CALL PROCEEDING
  55. 55. NIS 94-80nn World Trade IN Section 3: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Call Processing 13 December 1996 Page 41 No early setup messages are sent if a speech path has already been set up. This will be the case if: • There has already been user interaction earlier in the call. • The call has tried unsuccessfully to connect (ACM, but not ANS, has been received from the terminating side). When the call is finally routed, the terminating side will eventually return the following ETSI ISUP messages to the DMS SSP: ACM ANS These are the messages that would normally cause the speech path to be set up to the caller. However, since the speech path has already been set up to handle user interaction, these messages do not need to be relayed to the originating side, so they are simply discarded by the DMS SSP. Connecting to an External IP The DMS SSP sets up a link to the external IP by sending a PRI SETUP message on an outgoing PRI trunk. The external IP responds by sending the following PRI messages to the DMS SSP: 1. CALL PROCEEDING. This message is in response to the initial SETUP message. 2. ALERTING. This message causes the speech path to be set up between the caller and the external IP. 3. CONNECT. This message indicates that the link to the external IP has been established successfully, and user interaction can begin. Note: The connection between the DMS SSP and the external IP need not be direct. Although the outgoing trunk from the DMS SSP will be ETSI PRI, setting up a link to an external IP may involve interworking with other agents. However, depending on how the address of the external IP is specified, there may be restrictions on interworking; see Appendix D for details.
  56. 56. Section 3: World Trade IN NIS 94-80nn Call Processing SuspendedRelease 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 42 13 December 1996 Disconnecting From an External IP When the SCF signals that user interaction is complete (by sending an INAP DFC operation to the SSF), the DMS SSP breaks the connection to the external IP by sending a PRI DISCONNECT message with Cause value 16 (normal call clearing). The external IP responds with a PRI RELEASE message, and the DMS SSP completes the disconnection by sending a PRI RELEASE COMPLETE message to the external IP. The speech path between the caller and the DMS SSP remains open, and can be used for subsequent user interactions (either with the external IP or with the DMS SSP’s integrated IP). However, subsequent user interaction using the external IP will require the DMS SSP to make a new connection to the external IP. Note: The SRF can initiate disconnection of the external IP by sending a PRI DISCONNECT to the DMS SSP. If the external IP disconnects before it has answered a connection attempt, the SSF reports this to the SCF by returning an ETCFailed error in response to the ETC operation. If the external IP disconnects after a connection has been established, the SSF FSM simply returns to state Waiting For Instructions (the SSF assumes that the IP has informed the SCF). 3.3.3.2 Sequence of Events The sequence of events for user interaction via an external IP is as follows: 1. Before receiving an INAP ETC operation: - The SSF FSM is in state Waiting For Instructions. - O_BCSM call processing is suspended. - The SSRM (with which no interaction has yet taken place) is in state Idle. 2. When the SSF receives an INAP ETC operation from the SCF, the following call processing actions occur within the DMS SSP: - The SSF FSM moves to state Waiting For End Of Temporary Connection. - If no speech path to the caller exists, the DMS SSP sets one up, as described in Setting Up a Speech Path. - The DMS SSP sets up a link to the external IP, as described in Connecting to an External IP.
  57. 57. NIS 94-80nn World Trade IN Section 3: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Call Processing 13 December 1996 Page 43 3. When the external IP receives the SETUP message from the DMS SSP, the following actions occur within the IP: - A CALL PROCEEDING message is sent to the DMS SSP in response. - An ALERTING or PROGRESS message is sent to the DMS SSP, followed by a PRI CONNECT message, which establishes the connection with the DMS SSP. - The SSRM moves to state Connected. - The SRF sends an INAP ARI operation directly to the SCF to establish the direct connection between the external IP and the SCF. 4. The calling party is now through connected to the tone and announcement capabilities provided by the external IP. 5. User interaction can begin, as described in the specification DMS Implementation of CS-1R INAP (ETSI Core INAP Subset), and summarised in Figure 9. No further ETSI ISUP interaction is necessary during interaction with the user. 6. The SCF terminates user interaction by sending an INAP DFC operation to the SSF. The following call processing actions take place: - The SSF sends a PRI DISCONNECT message to the external IP with Cause value 16 (normal call clearing). - The external IP acknowledges by returning a RELEASE message. - The SSF sends a RELEASE COMPLETE message to the external IP. - At the external IP, the SSRM moves to state Idle. - At the DMS SSP, the SSF FSM moves to state Waiting For Instructions. The speech path to the caller remains open. Any subsequent interaction uses the speech path already set up. 7. The external IP can initiate disconnection by sending a PRI DISCONNECT message to the DMS SSP. The DMS SSP responds by sending RELEASE to the external IP, and the external IP completes disconnection by sending RELEASE COMPLETE to the DMS SSP. The effect on the SSRM and SSF FSM are the same as for SCF-initiated disconnect (see step 6). See Appendix D for details of the parameters of the PRI messages involved in external IP connection and disconnection.
  58. 58. Section 3: World Trade IN NIS 94-80nn Call Processing SuspendedRelease 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 44 13 December 1996 At any point while call processing is suspended, the SCF can send a ResetTimer operation to the SSF. The effect of ResetTimer is to restart the TSSF timer, which is used to control the amount of time for which the SSF will wait for some kind of response from the SCF (see Section 3.5.2.1 for more information about TSSF). Note: The SCF is allowed to send only one ResetTimer operation before sending some other kind of response to the SSF (e.g. ETC, Connect). However, after sending such a response, the SCF can send as many ResetTimer operations as it wishes. This is illustrated in Figure 9. 3.4 Resumption of O_BCSM call processing 3.4.1 Call Completion (Connect) O_BCSM call processing typically resumes when a Connect operation is sent from the SCF to the SSF to indicate that a call should be routed to a specified destination, thus successfully completing IN interaction. Two types of routing information may be provided: dRA destinationRoutingAddress parameter A destination routing address (a complete or partial replacement for the original called party address). cAP CutAndPaste parameter Optional cut-and-paste instructions on how the original dialled number should be manipulated to generate a new called party address. There are two possibilities: • The SCF can provide a complete replacement number in the dRA parameter, in which case no cAP parameter is supplied. Note: If there is no cAP parameter, any digits that arrive after Connect is received are ignored. • The SCF can provide a replacement prefix in the dRA parameter, in which case the cAP parameter specifies how many prefix digits should be removed from the original dialled number and replaced. For example, a Connect operation might replace a general-purpose IN prefix in the original dialled number (e.g. 0800) with the prefix of a specific switch where the requested service is actually provided.
  59. 59. NIS 94-80nn World Trade IN Section 3: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Call Processing 13 December 1996 Page 45 Note: If the SSF receives a Connect operation with a cAP parameter of 0, the effect is to append the dialled digits to the destination number supplied in Connect. Note: DMS SSP digit translation takes place at two points: • On the number initially dialled, e.g. to take into account the caller’s customer group. • After the IN query, which means that further digit manipulation may take place before routing. The resumption of call processing on receipt of a Connect is illustrated in Figure 10. The ETSI ISUP interactions implied by receipt of a Connect take place after call processing has resumed, and are described in Section 4.1. Figure 10 Resumption of call processing on receipt of a Connect Calling party Dialled digits (in-band) CCF / BCSM Digit manipulation via DMS translations IN interaction triggered on CdPN Result of IN query used to manipulate full CdPN (dRA replaces all or first n CdPN digits) SSF SSF sends InitialDP SCF SCF sends Connect INAP operation parameters Called party Onward routing More digits may reach SCF via SRF interaction with calling party (no effect on BCSM or SSF) Mandatory service key, optional CdPN Mandatory destinationRoutingAddress (dRA); optional cutAndPaste to replace prefix Dialled digits (out-of-band) Digit manipulation via DMS translations
  60. 60. Section 3: World Trade IN NIS 94-80nn Call Processing SuspendedRelease 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 46 13 December 1996 3.4.2 Call Clearing (ReleaseCall) If the SCF determines that a call cannot be completed (e.g. because the caller is not authorised), it sends a ReleaseCall operation to the SSF. This operation provides a releaseCause value to be used in initiating ETSI ISUP call clearing; for example: 21 (call rejected) 31 (normal unspecified) The mapping between releaseCall values and ETSI ISUP Cause values is described in Appendix E. The ETSI ISUP interactions implied by receipt of a ReleaseCall take place after call processing has resumed, and are described in Section 4.2. 3.5 Error Handling Note that if errors are detected while call processing is suspended, no action requiring ETSI ISUP interaction takes place until call processing is resumed and the call can be completed or cleared. 3.5.1 Errors Detected by INAP 3.5.1.1 Errors Detected by the SCF While O_BCSM call processing is suspended, a number of errors may be detected and reported by the SCF in response to: • An InitialDP operation sent by the SSF • An AssistRequestInstructions operation sent by the SRF These are reported in Return Error components in TCAP END messages. The SSF terminates the SCF/SSF dialogue and initiates backward call clearing with an appropriate Cause value (31 = normal, unspecified), which ensures that the caller hears an appropriate tone. 3.5.1.2 Errors Detected by the SSF/SRF While O_BCSM call processing is suspended, the SSF or SRF may detect errors in INAP operations sent by the SCF, as summarised in Table 2.
  61. 61. NIS 94-80nn World Trade IN Section 3: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Call Processing 13 December 1996 Page 47 In each case, the error is reported to the SCF in a Return Error component in a TCAP CONTINUE message. The SCF has the option of clearing the call with a ReleaseCall operation or taking some other action. 3.5.2 Timer Expiry This section describes how the SSF handles the conditions that result from the expiry of one of its internal timers. There are two such timers: TSSF and TSRF. The SSF uses both these timers to guard against excessive call suspension times while waiting for IN processing. a. This is detected by the SRF when the caller’s response is not as specified by the SCF. b. No INAP errors are reported for this operation. Table 2 INAP operation errors reported by the DMS SSP while call processing is suspended Operation Error ETCFailed ImproperCallerResponsea MissingParameter ParameterOutOfRange RequestedInfoError SystemFailure TaskRefused UnexpectedComponentSequence UnexpectedDataValue UnexpectedParameter ActivateServiceFiltering CallInformationRequest Connect ConnectToResource DisconnectForwardConnection EstablishTemporaryConnection FurnishChargingInformation PlayAnnouncement PromptAndCollectUserInformation ReleaseCallb ResetTimer
  62. 62. Section 3: World Trade IN NIS 94-80nn Call Processing SuspendedRelease 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 48 13 December 1996 Note: The usage of TSRF depends on whether an integrated or external IP connection is being used for user interaction. 3.5.2.1 Expiry of TSSF The SSF starts (or restarts) the timer TSSF: • When the SSF FSM moves into state c (Waiting For Instructions) (e.g. after sending an InitialDP or EventReportBCSM operation to the SCF). In this situation, the timer can have a value from 1 to 10 seconds. • When the SSF FSM moves into state d (Waiting For End Of User Interaction) (e.g. after receiving a CTR operation from the SCF). In this situation, the timer can have a value from 1 to 60 minutes. • When the SSF FSM moves into state e (Waiting For End Of Temporary Connection) (e.g. after receiving a ETC operation from the SCF). In this situation, the timer can have a value from 1 to 60 minutes. • When the SSF receives a ResetTimer operation from the SCF. In this situation, the value of the timer is specified in a parameter of the ResetTimer operation, and may be one of the following: 1 to 10 seconds 1 to 10 minutes 15, 20, 25, 30, 35, 40, 45, 50, 55 or 60 minutes If the specified timer value is not one of the above, the nearest legal value is used. If the SSF does not receive a valid operation from the SCF before the TSSF timer expires, the following call processing actions occur within the SSF: 1. The SSF FSM moves to state a (Idle). 2. The SSF performs a user-initiated abort (see Section 3.5.4). Each time the SSF receives a valid operation from the SCF, it restarts the TSSF timer. If an operation received from the SCF contains an error, the TSSF timer continues to run after the SSF has sent an error indication. The SCF therefore has the opportunity to send a correct operation before the timer expires.
  63. 63. NIS 94-80nn World Trade IN Section 3: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Call Processing 13 December 1996 Page 49 An external IP can close the connection with the DMS SSP, either during or after connection of the speech path, by sending a PRI RELEASE message to the DMS SSP. On receiving this RELEASE message, the SSF: • Stops the TSSF timer • Sends an ETCFailed error to the SCF (only if the external IP hasn’t yet answered; i.e. it hasn’t returned a PRI CONNECT) • Moves to state Waiting For Instructions • Restarts the TSSF timer with its WFI value 3.5.2.2 Expiry of TSRF This section describes the use of the TSRF timer if an integrated IP connection is used for user interaction. Note: If an external IP connection is used for user interaction, standard signalling system protocol timers are used to control connection setup. TSRF is not used. The SSF starts the timer TSRF when the SRSM moves into state 2 (Connected) after receiving a CTR operation from the SCF. The timer can have a value from 1 to 10 seconds. If the SRF does not receive a valid PA or PC operation from the SCF before the TSRF timer expires, the following call processing actions occur within the SSF: 1. SRF resources are released. This is equivalent to receiving a DFC operation from the SCF. 2. The SRSM moves to state 1 (Idle). 3. The SSF FSM moves to state c (Waiting For Instructions). 4. The TSSF timer (maximum value 10 seconds) is restarted. 5. If the TSSF timer expires without the SSF receiving a valid operation from the SCP: a. The SSF FSM moves to state a (Idle). b. The SSF performs a user-initiated abort (see Section 3.5.4). In this situation, the TSSF timer acts as a backup to the TSRF timer.
  64. 64. Section 3: World Trade IN NIS 94-80nn Call Processing SuspendedRelease 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 50 13 December 1996 Note: The expiry of the TSRF timer has the same effect as the receipt of a DFC operation from the SCF. The SSF restarts the TSRF timer under the following circumstances: • When it receives a valid PA or PC operation from the SCF • After sending a SRR operation to the SCF (on successful completion of a preceding PA operation) • After sending the Return Result for a preceding PC operation If an operation received from the SCF contains an error, the TSRF timer continues to run after the SSF has sent an error indication. The SCF therefore has the opportunity to send a correct operation before the timer expires. 3.5.3 Errors Detected by TCAP 3.5.3.1 Errors Detected by the SCF If the SCF detects an error in the TCAP component in which an INAP operation is sent, it sends a Reject component in an END package to the SSF. The SSF responds by terminating the dialogue and initiating backward call clearing by sending a REL message with a Cause value of 2 (network termination). 3.5.3.2 Errors Detected by the SSF If the SSF detects an error in the TCAP component in which an INAP operation is sent, it sends a Reject component in a CONTINUE package to the SCF. The action taken depends on the SCF, which can either resend the component or release the call. 3.5.4 User-Initiated Abort Either the SCF or the SSF can abort a dialogue by sending a TCAP ABORT package. This is called user-initiated abort (where “user” refers to INAP as being the user of the TCAP layer). User-initiated abort can occur when: • The caller hangs up during call processing • The TSSF timer expires The SSF responds to a user-initiated abort by initiating backward call clearing, as described in Section 4.2.
  65. 65. NIS 94-80nn World Trade IN Section 3: PRE 0.2 (draft) Release 4 ETSI ISUP / INAP Interworking Call Processing 13 December 1996 Page 51 3.5.5 Errors Detected by ETSI ISUP The only errors that can be detected by ETSI ISUP while call processing is suspended are problems with setting up and through-connecting a speech path back to the caller for user interaction (see Section 3.3), e.g. caller hangs up or network problem. In either case, the call attempt will be cleared using standard ETSI ISUP call clearing messaging. When the O_BCSM informs the SSF that the call has been cleared, it will inform the SCF by sending a TCAP ABORT package.
  66. 66. Section 3: World Trade IN NIS 94-80nn Call Processing SuspendedRelease 4 ETSI ISUP / INAP Interworking PRE 0.2 (draft) Page 52 13 December 1996

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