Betwee n CP ' s on the Clearing House.doc

PRODUCT HANDBOOK

IP EXCHANGE
An IP Clearinghouse Solution from BT Wholesale

Version No: 3 Page 1 of 16
Date of issue: 01 April 2008
Product Handbook – IP Exchange
Owner of Document: Steve Sherry
Contact No: 07917 025050

1.1 FEATURES OVERVIEW........................................................................................................................................3
1.2 FUNCTIONALITY AND USAGE SCENARIO.................................................................................................................4
1.3 CREDIT VETTING .............................................................................................................................................9
1.4 BT BILLING REPORTS ......................................................................................................................................9
1.5 COMPATIBILITY TESTING..................................................................................................................................10
1.6 SERVICE ESTABLISHMENT.................................................................................................................................10
1.7 PORT CAPACITY AMENDMENT...........................................................................................................................11
1.8 NUMBER MANAGEMENT – ENUM UPDATES......................................................................................................11
1.9 NUMBER MANAGEMENT – CUSTOMER NUMBER RANGE HOSTING............................................................................11
1.10 NUMBER MANAGEMENT – PORTABILITY............................................................................................................11
1.11 NUMBER MANAGEMENT – SUB-ALLOCATION OF BT NUMBER RANGES...................................................................11
1.12 SECURITY OF TRANSPORT BETWEEN CP AND BT.................................................................................................12
1.13 IP VERSION................................................................................................................................................12
1.14 DNS.........................................................................................................................................................12
1.15 SIP TRANSPORT...........................................................................................................................................12
1.16 CODECS SUPPORTED .....................................................................................................................................13
1.17 TRANSPORT OF FAX ...................................................................................................................................13
1.18 TRANSPORT OF AUDIO TONES – DTMF TONES...............................................................................................14
1.19 BANDWIDTH AND CALL CONTROL....................................................................................................................14
1.20 CALLING LINE IDENTITY AND PRESENTATION NUMBER SUPPORT............................................................................14
1.21 CLI WITHHELD ..........................................................................................................................................14

1 OUTLINE OF THE SERVICE
IP Exchange is a new product from BT Wholesale positioned to meet the requirement of the emerging IP
communications market for a clearing house which connects together disparate IP islands, supporting VoIP to
VoIP calling, calls to and from the PSTN, and calls between Video CPE, PC’s & 3G Mobiles.

IP Exchange offers competitive market rates to deliver calls originating from an IP communications providers
network and will pay a settlement fee for calls terminating on that network, depending on commercial
agreements.

IP Exchange will Support:-

VoIP Gateway -
• Break Out - from a customer’s IP network to BT and other UK fixed PSTNs, Mobile and International
Networks.
• Break In – from BT and other UK fixed PSTN, Mobile and International networks to a customer’s IP
network.
• Clearing House - VoIP to VoIP calls between IP Exchange Customers’ IP networks including BT Retail’s
own services.

2 SCOPE
With the growth of VoIP calling, nationally and internationally, the requirement and opportunity for VoIP
interconnect services becomes significant.

BT Wholesale has outlined a market opportunity for a clearing house service for VoIP that provides a
transcoding capability between the SIP servers of VoIP Service Providers.

For service providers this reduces the need and unnecessary overhead of commercial and technical
bilateral peering agreements and at the same time widens the community of interest for VoIP users. For
BT, a VoIP clearing house service stimulates interconnect based on ENUM and conveyance revenues
Contact No: 07917 025050

where VoIP bypass is a realistic risk, and in doing so load the 21C Network, thereby spreading the risk of
investment.

The usage of VoIP worldwide has already exploded due largely to players such as Vonage and Skype.
Skype particularly has been a phenomenon. Offering free calls between Skype users, its software or PC
client has been downloaded by 164m users worldwide, of which 50m are reportedly active users.
However, with more service providers entering the market, the monetisation of VoIP traffic is increasingly
at the forefront of providers’ strategies.

Most current VoIP offerings are closed communities whereby the ability to both make and receive VoIP
calls is either not possible (unless an associated PSTN numbering range is given) or confined to on-net
calling within a single ISPs community. Already, however, new entrants such as XConnect, InfiniRoute
and Interoute are beginning to provide VoIP peering and clearinghouse services to enable the expansion
of VoIP communities. The emergence of ENUM, as a registry database, will facilitate this further.

The IP EXCHANGE solution is incremental to that proposed within 21CN. However, BTW has the
opportunity to recreate the interconnect community in IP that exists for PSTN. The option for VoIP
calling communities will therefore be available for BT and it’s interconnect partners.

3 KEY FEATURES AND AVAILABILITY

1.1 Features Overview
The underpinning requirement related to a clearinghouse service is a widening of on-net VoIP calling
attributes to users not provisioned by the same service provider. Instead of operating in a closed
community, many ISPs want to offer VoIP calling whereby their users will be able to make and receive
VoIP based calls with users from other ISPs.
This has a commercial as well as a technical implication. The basic premise of the clearinghouse is that
it will reduce the overhead of each ISP or service provider negotiating bilateral agreements for
interconnecting VoIP gateways, including end user address discovery, e.g. Carrier Registration User
ENUM (CRUE).
There is not one standard for VoIP, with users making VoIP calls through different and incompatible PC
clients (e.g. Communicator and Skype), routers/modems (e.g. Vonage and Voyager) and access
methods (e.g. IPStream, LLU, cable and potentially 3G mobile). However, from a user perspective this
should not be a barrier.
Provided that the VoIP service is based on SIP – albeit SIP deployments are not standard – VoIP service
providers will be able to stretch their on-net privileges for users to users managed by other service
providers.

Contact No: 07917 025050

High Level Architecture

Billing Routing Provision Mgt

BT
Clearinghouse

ITSPs PSTN

Mobile
Enterprises Network IP Carriers
Operators

1.2 Functionality and Usage Scenario
To enable VoIP on-net communities to be expanded to include other service providers, the basic
construct of a BT VoIP clearinghouse will require interconnect capability between BTs SIP server and
those of other service providers.

In many cases, however, the VoIP service of a given Service Provider will be based on a different SIP
variant to that of BT, which will entail the BT clearinghouse having a transcoding capability to translate
and convert VoIP call routing information.

BTW will register and maintain an operator’s numbers on the ENUM (CRUE) directory. Incoming calls
from the internet to a VoIP operator’s number will be pointed to the BT SIP gateway. This places the call
on to BT’s IP network, with a full range of security and value-add functions (e.g. financial settlements,
transcoding, authentication, anti-spam, identity fraud protection, user-defined filters etc).

Key clearing house functions include:
• Gateway/clearing house for transporting VoIP bytes
• Logging of call routing information: origination, termination and transit points
• Logging of call type information: packet-size, call period
• Transcoding of SIP information
• Metering engine for bill creation and settlement between service providers

A VoIP clearinghouse is more than just a termination point. It is a service provider for other service
providers, offering a mixed portfolio of termination, financial services, and enhanced applications. Many
clearinghouses perform the following functions:

• a single point of contact for termination of telephony minutes worldwide
• a source for termination rates to specific destinations

Contact No: 07917 025050

• financial accounts management
• settlement of accounts between carriers
• credit risk assessment between carriers
• receivable processing between carriers (financial settlements)
• quality of service (QoS) monitoring and provisioning
• bandwidth and IP access provisioning
Currently PSTN operators charge each other for transport and termination of telephone calls with a
guaranteed quality of connection. If we assume the business model for NGN is similar to PSTN then
operators of NGN VoIP networks will need to agree commercial and technical SLAs based on ITU
recommendations for security and performance as high voice quality is an end to end function.
VoIP is susceptible to network congestion, denial of service attacks and viruses, due to the shared IP
network resources employed and hence management by a reliable supplier will be essential, particularly
for business applications.

THE NEW WORLD OF IP EXCHANGE

Call Number Billing Management
Manager translation & information
Charging

BT
CP BBV Communications CP BBV
network IP clearing house IP network

SS SS7 /
7 IP
PSTN Mobile
network network

Connects any-to-any

4 SERVICE EXCEPTIONS
There are service exceptions involving:-

• Fax outside codec G.711 (T.38 and up-speed to G.711 to be supported from early 2008), Fax calls
using G.729 may operate successfully however this is not guaranteed.
• Short Message Service and Text Messaging are NOT supported.

Break Out Calls to:

Contact No: 07917 025050

(i) 1XX, Note: These are generally CP specific and should be dealt with by the CP within their
own service domain. Calls to the Operator 100 and 123 Speaking Clock, are allowed but are
charged to the CP.
(ii) 112 European Emergency Services, CPs are required to change all calls originating as 112,
to 999 before passing these to IP Exchange should the 999 Access option be chosen as
party of the service contract.
(iii) 118 XXX, Calls to DQ services are allowed, and are charged at a rate relevant to the DQ
services plus the cost of conversion for IP Exchange.
(iv) 1XXX and 1XXXX codes, Carrier Pre-Select and Indirect Access codes are NOT supported
currently.
(v) 070 Personal Numbering Services, (can be supported but only by commercial agreement,
special rates are applicable).
(vi) Dial up Internet Services are NOT supported.

Number Export
IP Exchange does not currently support the Exporting of a Number from a connected CP, this is a
planned activity and will be delivered during 2008 in conjunction with other work being performed by BT
Group. Many other services are requiring similar Export capability and it is necessary to combine the
requirements so as to minimise the disruption and development.

5 ACCESS OPTIONS
Access to IP Exchange – A range of options for connection to IP Exchange are available either with or
without resilience. These include:

Access Method Connection Type Resilience Options
Option 1 - World Wide Web Virtual Connection using existing Connection to more than one IP
(Public Internet) or additional bandwidth over the Exchange POP.
Internet
Option 1 - BT’s IP ‘Colossus’ BT NetFlex (Clear Bandwidth) at Via Separate BT NetFlex circuits
Network over 100 PoPs in the UK or Via the Internet

Option 2 - Neutral Access 10Mb, 100Mb or 1Gb Fibre or Via alternative NAP at another
Points (NAP) or Direct Access Metallic I/F at Telehouse – North, site, or Via Separate BT NetFlex
(includes optional WWW fall London. Telecity – Manchester. circuits or Via the Internet
back routing in failure mode) Requires Customer to purchase
Tie or Bandwidth circuits to meet
at the NAP.

Contact No: 07917 025050

Option 3 - Direct Connection Bandwidth connection to the IP Via alternative DC connection to
(includes optional WWW fall Exchange PoPs in Birmingham other IP Ex PoP, or Via
back routing in failure mode) and/or Kingston (London) alternative NAP at another site,
or Via Separate BT NetFlex
circuits or Via the Internet

* Notes:
a. Access circuits are not included as part of the BT IP Exchange service but can be ordered separately
– please contact your Account Team.
b. To ensure an acceptable customer experience for voice and video calls the customer’s service to
their end user must provide sufficient capacity at all times.
c. The product will use the SIP Protocol based on supporting a range of codecs including G.711 and G.729.
d. For the NAPs at Telehouse North (London) and Telecity (Manchester), full resiliency of the backend
circuits (fibres) is provided.
e. All connectivity between Telehouses at same location and within building connectivity is the responsibility
of the customer.

6 QUALITY OF SERVICE
The IP Exchange service is designed to deliver a reliable and resilient customer experience through the
use of tried and tested components, sourced from our strategic partners in industry.

MOS (Mean Opinion Score) Probes - It is planned to add voice quality probes to monitor voice quality

Contact No: 07917 025050

across the platform in 2008.

QoS MIS reports – a range of Management Information System reports will be developed in consultation
with early adopter Customer requirements.

Platform Resilience – provided for all customers - access session border controllers are deployed in resilient
pairs within the same location and additional layers of resilience can be achieved by bespoke design.

Access Service Assurance – Customers have the option of gaining additional service assurance by having
the access method (Internet vs Direct Access vs Direct Connection) resilient, however the access maybe back
to the same Session Border Controller resilient pair.

Geographic Service Assurance – additionally Customer can elect to match their own call server resilience
through a second proxy accessing a second platform resilient pair of session border controllers deployed in
another geographic separate BT site.

Signalling Monitoring – The signalling interfaces within or connecting to the service will be monitored on a
continual basis. This will ensure adherence to standards and agreed or contracted service responsibilities.

Bandwidth and Call Control - It is the CP’s responsibility to keep within subscribed bandwidth and the
maximum number of concurrent calls allowed (this will include bandwidth consumed for ingress and
egress calls).

In the case that CP delivers more traffic to a BT POP, BT’s network will return the SIP Response 503.
The only exception to this rule will be for emergency calls, which will be allowed regardless of subscribed
limits.

The method of access to the service and the service quality of the customer’s own IP network will also
influence the end-to-end quality of the IP Exchange service.

7 PRICING
The following charges will be applicable for the service. Current prices will be provided upon request:

Pre-Ordering Compatibility testing charge – this charge will only be applicable where a customer’s
call server equipment is not recognised as being compatible with the BT service and hence
interoperability testing is required. This will be done prior to service establishment.

Service Establishment Provision Charge – a non-reoccurring, cost orientated provision charge to
cover all initial provisioning activities and service establishment.

Port Management Charge – covers the bandwidth capacity, method of access, resilience level and
management of customer capacity e.g. capacity changes, ENUM number management, data build etc.

Port charges are invoiced monthly in advance and are available in the following access types:-

Public Internet (WWW) access – site resilient
Public Internet (WWW) access – Geo site resilient (customer traffic is load shared across two
geographically separate sites.
Direct Access via a NAP (Neutral Access Point) – site resilient only.
Direct Access to POP (Point of Presence) site – site resilient only.

Customers can elect to take any combination of the above port types to provide the level of service
assurance they require.

The initial Port requirement carries a 12 month contractual term.
Minimum order quantity of any Port type at any site is 30 Ports.
Contact No: 07917 025050

Customers must maintain a minimum Port quantity of 30 Ports (of a single access type at a single site).
•
Call conveyance – calls will be invoiced monthly in arrears on a pence per minute basis measured by
the second and rounded up to the next second.
Call rates are available as:-

• UK Geographic calls – a blended rate, variable by time of day to all fixed and IP Networks.
• BT Only fixed and IP networks variable by time of day (where the customer has the ability to
segregate BT traffic from other network traffics), and volumes are significant.
• Mobile – variable by terminating network and time of day.
• International – variable by terminating network/destination country.

Call termination – commercial settlement will be paid for calls terminating a customer’s IP Network.

Number Porting – This is based on the nominal Regulatory pricing structure available from Openreach,
however BT Wholesale apply an additional sum on to of the regulatory price to cover the increased
workload in applying Number Porting changes. These will be dealt with on a Single or Multi-Line basis.

Number Sub-Allocation – there is a one off (non-reoccurring) set up charge per number sub-allocated
to cover BT’s internal costs of breaking out, re-routing and sub-allocating numbers.

8 BILLING

1.3 Credit Vetting
All customers will be credit vetted using the standard BTWM credit vetting process.
Credit Vet 1 is a high level check of the trading entity and its directors.
Customers will be asked to provide traffic profiles as part of the initial CRF information gathering process.
Customers will also be asked to select a ‘Barring Profile’ which limits the customer’s fraud liability by
electing not to pass certain high value call types e.g. fixed fee NTS and/or all PRS calls.
The customer’s traffic patterns will be loaded into and monitored by the BTW anti fraud system Rapier.
Credit Vet 2 is based on the customer’s forecast traffic profile and call barring option selected.
Depending upon the outcome of the second credit vet Customers may be asked to provide financial
surety as set out in the BTWM Credit Vetting Process. In some cases Customers may be placed on a
billing periodicity less than the standard 30 days (see below).
Direct Debit is the preferred method of payment.
Pre-Payment
Pre-payment is an option for a small number of CPs wishing to use IP Exchange, CPs are asked to lodge
a sum with BT that is then reduced accordingly depending on the revenues generated by the CP. Note:
this is a manual process and CPS are closely monitored.

1.4 BT Billing Reports
Billing will be handled via the standard BTW Interconnect Billing process and normally invoiced on a
monthly basis. Customers will normally have 30 days in which to pay the previous period’s invoice (this
may vary subject to credit vetting results).
Invoices are backed up by an aggregated CDR (Call Data Record) feed which shows the volume, time of
day and value of calls aggregated by call type and terminating network. The back up feed is intended to
aid invoice verification and does not include details of the originating end user number.
It is assumed that the Customer has the ability to generate their own CDRs for billing their end users.
Contact No: 07917 025050

Customers will be expected to invoice BT for calls terminating on their network containing the same
granularity of information as outlined above. For clarity; BT will not be providing this information to
Customers.

9 ORDERING PROCESS AND PROVISION
Your Account Manager (or Sales Specialist) will be able to assist you in the ordering process in the first
instance and will have the necessary Contractual documentation, and Customer Requirements Form
(CRF) to gather your requirements.

A Technical Account Manager (TAM) and Commercial Manager (CM) will be appointed to support the
Customer through contract signature and where necessary any Compatibility Testing and associated
provision activity.

1.5 Compatibility Testing
To ensure that the Customers equipment and software version are fully compatible with the BT IP
Exchange platform, a degree of interoperability testing will be necessary. The length of the testing cycle
is dependant upon a number of factors including the services to be used and the availability of Customer
test engineers etc.

Once a signed contract has been received by the Commercial Manager the TAM will book the next
available test slot and communicate this ‘time window’ to the Customer. The TAM may also ask for a re-
testing questionnaire to be completed, which usually helps to reduce the number and complexity of tests
required.

The TAM will also manage the customer’s numbering requirements as specified on the initial CRF. Any
data build work in the PSTN must follow a regulated DMA (Data Management Amendment) process and
takes not less than 30 working days to complete. Should a Customer’s numbering requirements be
complex a ‘Complex DMA may be required which has a longer lead time of not less than 75 working
days. The TAM will advise which type of DMA will be required.

The TAM will also manage any 999 service establishment aspects of a Customer requirement and advise
on processes to update a Customer’s end user details onto the BT ESDB (Emergency services Data
Base).

Once a Customer has successfully completed Compatibility Testing, the TAM (Technical Account
Manager) will hand over the CRF to the IP Exchange Customer service Centre Team in Wolverhampton
who will manage Service Establishment. The TAM will advise the Customer of the likely timescale for
Service Establishment and the ‘live’ SIP address that should be loaded onto the Customers equipment.

1.6 Service Establishment
The IP Exchange Customer Service Team in Wolverhampton can be contacted on 0800 077 8247.

The Customer Service Team will manage all remaining aspects of Service Establishment, Port capacity
provision, loading data on ENUM, any Number Ports one in-service and the live platform and open billing
accounts.

The Customer will be contacted by our engineers once Service Establishment work has been completed
and asked to send some test calls to confirm settings on both the BT IP Exchange Platform and the
Customers equipment have been provisioned correctly and calls can be passed.

On completion of Service Establishment the Customer Service Team will advise the Customer by email
and receive a Welcome Letter, Customer Service Plan and Product Handbook.

Contact No: 07917 025050

1.7 Port Capacity Amendment
Amendment to a Customer’s Port Capacity is achieved by submitting an ‘Additional ports’ CRF
(Customer requirements Form) clearly stating the additional Port type and capacity required. The
minimum order increment or decrement capacity is 30 Ports but any number above this minimum is
acceptable i.e. 35 Ports. In addition BT will provide a ‘buffer’ of 10% additional Port capacity free of
charge to facilitate seamless growth. A further 5% of the bandwidth ordered will be reserved for 999
services, which will not be available for normal calls, however 999 calls can consume any or all of the
115% of bandwidth ordered.

The CRF should be emailed to the Customer Service Centre who will arrange provisioning / cessation
activity and liaise with the Customer’s TAM as necessary.

1.8 Number Management – ENUM Updates
As a Customer either obtains new telephone numbers through, OfCom allocation (see 9.5), BT Sub-
Allocation (see 9.7) or Number Import (see 9.6) they will need to update the IP Exchange ENUM routing
data base. The Customer should submit a ‘Modify Data’ CRF completing the spreadsheet in section 5
and entering instructions in section 6.

The CRF should be emailed to the Customer Service Centre who will arrange provisioning / cessation
activity and liaise with the Customer’s TAM as necessary.

It is the Customer’s responsibility to ensure that the BT IP Exchange Customer Service Centre are
provided with timely updates of Numbering changes (additions and losses) to ensure service levels are
maintained.

1.9 Number Management – Customer Number Range Hosting

BT IP Exchange can host numbers allocated to Customers and any new number blocks obtained from
OfCom should be notified to the BT Commercial Manager for inclusion in contract and built into ENUM as
described above in section 9.4.

1.10 Number Management – Portability
Please refer to the Number Portability and Number Sub-allocation Handbook.

1.11 Number Management – Sub-Allocation of BT Number ranges
BT has geographic numbers allocated to IP Exchange for sub-allocation to Customers to support their
service. Customers should contact their TAM (Technical Account Manager) who will arrange for the
numbers to be sub-allocated. There is a one off set up charge per number (see section 7) which will be
billed to the customer periodically. A full list of Number Ranges available is available at
http://www.btwholesale.com/pages/static/Products/Interconnect/IP_exchange.html

Pleas refer to the IP Exchange Number Porting and Number Sub-allocation Handbook for more details.

10 TECHNICAL DETAILS
This document covers the interface between BT’s call server and the CP’s call server. It is assumed that
only SIP will be supported for the signalling between the two carriers. H.323 and SIP-I are out of scope of
the service offering.

The following types of calls will be supported across this interface:
• Voice calls to PSTN destinations (UK and International)

Contact No: 07917 025050

• Voice over IP and Video over IP will also be supported where the origination and the destination
are both on the BT Clearing House network.
• Emergency calls for only UK originated calls with prior agreement
• Service calls with prior agreement

For a CP to access the BT IP Exchange service, the CP must be able to support the following:

• A SIP proxy to interface to BT’s network over the internet.
• In addition, it is recommended that the CP provides secure access to their network by means of
a Firewall or a Session Border Controller.

Access to the BT IP Exchange network is provided across the internet. This can be provided by BT with
the following options:

• Changes to routing configuration and tunnelling of traffic from the CPs network across the
Internet to the IP Exchange system
• Internet access (BT Net Access)

Shortly after the initial
• Leased line access (High bandwidth services) to provide access direct to a VMP Node
(Manchester, Birmingham, Reading, London, Croydon plus Telehouse in London and
Manchester).
• Via a Network Access Point (NAP), these will be deployed across the country at major cities and
towns to allow for a more cost effective solution.

1.12 Security of transport between CP and BT
In order to provide secure access from the CP’s network into the BT network, basic security will be
provided by means of a firewall. The CP will need to define the signalling and media IP addresses which
will be used for this service. BT will not respond to any signalling and media from addresses which have
not been pre-agreed.

BT will only send signalling and media from defined IP addresses.

1.13 IP Version
IP version 4.0 will be supported.

IP Version 6.0 will not be supported

1.14 DNS
In terms of the CP interaction with BT’s network, DNS capability, including SRV and A record look up, will
not be supported.

1.15 SIP transport
RFC 3261 allows SIP requests to be sent using reliable or unreliable protocols: UDP, TCP, or SCTP.

For this service, the following SIP signalling message transport methods will be supported:
• UDP
• TCP

The following SIP message transport methods will not be supported at present:
• TLS

Contact No: 07917 025050

• SCTP
• IPSEC

The SIP signalling between the CP and the BT proxy will be based on the following IETF RFCs:
• IETF RFC 3261, "SIP: Session Initiation Protocol"
• IETF RFC 3262, "Reliability of Provisional Responses in SIP"
• IETF RFC 3264, “An Offer / Answer Model with SDP”
• IETF RFC 3325, “Private Extensions to SIP for Asserted Identity within trusted networks”
• IETF RFC 2976, “The SIP INFO Method”

1.16 Codecs Supported
1.16.1 Between CP’s on the Clearing House

The following minimum set of codecs will be supported:

• G.711 Alaw (20 msec packet size)
• G.729 (30 msec packet size)
• G.729 annex A (30 msec packet size)
• G.729 annex B (30 msec packet size)
• G.723.1 (6.3 Kbps) (30 msec packet size)
• G.728 (16 Kbps) (30 msec packet size)
• G.726 (16 Kbps)
• G.726 (24 Kbps)
• GSM
• G.722.2 AMR WB
• DTMF Transport as for RFC 2833
• DTMF Transport as for SIP Info (RFC 2976)

1.16.2 Between the CP and BT

For calls between the CP and PSTN

The following Voice codecs will be supported:

• G.711 A law (20 msec packet size)
• G.729 (30 msec packet size)
• G.729 annex A (30 msec packet size)
• G.729 annex B (30 msec packet size)
• DTMF transport as for RFC2833
• DTMF transport as for SIP Info (RFC 2976)

Inter-working of the different DTMF transport methods will not be supported.

1.17 Transport of FAX
The following two methods will be supported to transport fax tones:

• G.711 In band (For G.729 the correct detection of the tones and the resulting fax quality at the
far end may work but will not be guaranteed)

Contact No: 07917 025050

• ITU-T.38 transport after initial in band transfer of the Send Call Tone (CNG) will be supported
from May 2008 onwards.

If the far end CP does not support the method of transport of the tones, BT will not perform any form of
inter-working between the two different methods.

1.18 Transport of audio tones – DTMF TONES
The following methods will be supported to transport DTMF tones:

• In band (G.711 codec is preferred. With G.729 detection of the tones at the far end will not
always be guaranteed)
• RFC2833
• SIP Info (RFC 2976)

1.19 Bandwidth and Call Control
It is the CP’s responsibility to keep within subscribed bandwidth and the maximum number of concurrent
calls allowed (this will include bandwidth consumed for ingress and egress calls).

In the case that CP delivers more traffic to a BT POP, BT’s network will return the SIP Response 503.
The only exception to this rule will be for emergency calls, which will be allowed regardless of subscribed
limits.

1.20 Calling Line Identity and Presentation Number Support
Only network CLI Presentation and Restriction will be supported (for calls between the CP and the PSTN/
CPs). Presentation number will not be supported for calls between the CP and the PSTN. When the UK
SIP Spec is agreed CPs will be expected to migrate to the standard therein. This is expected to include
as a minimum the Network Number and additional a Presentation Number where appropriate.

1.21 CLI Withheld
For calls from the CP to IP exchange, the CP will indicate that CLI is not for CLI display purposes by use
of (a) RFC3261 Section 8.1.1.3 and 20.20 which describes the use of an "Anonymous" display field to the
From: header to indicate that the client is requesting privacy. (b) SIP Privacy Header which is described
by RFC 3323.

For calls from IP Exchange to the CP, the CP is required to implement both methods of CLI restriction a)
RFC3261 Section 8.1.1.3 and 20.20. (b) SIP Privacy Header which is described by RFC 3323. Note that
for both methods, the Restricted CLI should not be made available to the Called Party CPE.

11 FAULT HANDLING AND REPAIR
Customers can report faults 24/7 throughout the year to the IP Exchange Customer Service Team on
0800 077 8247. The repair service desk will ensure that the customer has proven the fault away from
their network before accepting the fault and then allocate a unique service identifier.

Repair handling teams will check IRAMS for known platform problems, record the fault instance on
SPACER-R and inform operations of the problems and request a resolution, SPACE-R will be updated
and the customer notified of the service restoration on completion.

Contact No: 07917 025050

12 SERVICE CESSATION
Customers can cease their entire service with IP Exchange by submitting a ‘cessation’ CRF reducing
their port capacity to zero. Customers need to give a minimum of 30 working days notice to facilitate re-
routing activity in the PSTN etc.

13 COMPLAINTS HANDLING
Any complaint regarding the IP Exchange service should in the first instance be directed to the helpdesk
for resolution on 0800 077 8247. Should a customer remain dissatisfied they should follow the escalation
procedure detailed in the CSP (Customer Service Plan).

14 ADDITIONAL INFORMATION
IP Exchange is not a PSTN emulation services and customers should be aware that some PSTN
features that are supported by ISUP signalling are not available with this product e.g. Ring Back when
Free, Malicious Call Trace etc.

The following documentation is available from your BT Account team:-

• Product Description
• Technical Service Description
• Customer Service Plan (CSP)
• Customer Requirements Form
• Contract

15 GLOSSARY OF TERMS
21CN 21st Century Network
AMR Adaptive Multi-Rate speech encoding
BTWM BT Wholesale Markets
CM Commercial Manager
CNG Comfort Noise Generator
CP Communications Provider
CRUE Carrier Registrations in User ENUM
DMA Data Management Amendment
DNS Domain Name Server
DSL Digital Subscriber Line
DTMF Dual Tones Multi Frequency
ENUM E-164 Number Mapping
GSM Global System for Mobile
IETF Internet Engineering Task Force
IMS Internet & Multimedia Services
IP Internet Protocol
IPSec IP Security protocol
ITU International Telecommunications Union
LLU Local Loop Unbundling
NGN Next Generation Network
POLO Payment to Other Licensed Operator
POP Point Of Presence
PSTN Public Switched Telephone Network
QoS Quality of Service
RFC Request for Comment
RTP Real Time Protocol
Contact No: 07917 025050

SIP Session Initiation Protocol
SIP-I Session Initiation Protocol - Interconnect
SCTP Stream Control Transmission Protocol
SLA Service Level Agreement
SRV Service Record Value
TAM Technical Account Manager
TCP Transmission Control Protocol
TDM Time Division Multiplexing
TLS Transport Layer Security
TNO Telecommunications Network Operator
UDP User Datagram Protocol
URI Universal Resource Indicator
VoIP Voice over the Internet Protocol

Contact No: 07917 025050

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