The document discusses signaling system 7 (SS7) and its components and protocols used in telephone networks for call setup and routing. Some key points: - SS7 uses out-of-band signaling to setup, manage, and tear down calls between switches instead of using the voice circuit itself. - Major components include service switching points (SSPs), signaling transfer points (STPs), and service control points (SCPs). SSPs initiate queries, STPs route messages, and SCPs process requests like number translations. - Protocols are divided into the user part and message transfer part. The user part includes ISUP for call setup and SCCP for non-circuit related messages.

1. i
i d
ad
H



2. i
i d
ad
H




Network

3. i
i d
ad
H
SS7

Tone or Pulse
Voice Mailbox
Call-waiting Tone
Multi-party
SMS






4. i
i d
ad
H
300-3400Hz



Call
“I’m busy!”
Voice
Trunk

5. i
i d
ad
H

Switch
A
User Traffic
Switch
B
Signaling Traffic

Switch
A
User & Signaling Traffic
Switch
B






Call Setup



(IN)



6. i
i d
ad
H
SS7

SS7
ITU
(Red Book)
SS7


SS7
ITU
SS7

Update


7. i
i d
ad
H
SS7
SS7 Protocols (Q.700
series)
Out-of-band




(ISDN)


8. i
i d
ad
H
Set up and clear down a call
Call forwarding
Provide Caller ID
Security access calls (CUG)
Circuit continuity check
Call holding
Notification to reset a faulty circuit
Charging information
Indication of national, international or
other subscriber
Indication that a called party line is free
Nature of circuit (satellite/terrestrial)
Subscriber busy signal

9. i
i d
ad
H
-
Service Switching Point
Signaling Transfer Point
Service Control Point


(SP)


(56Kbps or 64Kbps)
SCP

SCP
SCP
SCP
STP
STP
SSP
SSP
STP
STP
SSP
SSP
SSP
STP
SCP

10. i
i d
ad
H


ISDN

TE


11. i
i d
ad
H
STP
(STP)
(LE,TE)



12. i
i d
ad
H
Network Identifier
Cluster Identifier
Cluster Member
Cluster=1
Network=246
Cluster=2
1
1
STP
STP
2
2
STP
STP
3
3
4
4



SPC

13. i
i d
ad
H

14. i
i d
ad
H

15. i
i d
ad
H

16. i
i d
ad
H

17. i
i d
ad
H

18. i
i d
ad
H

19. i
i d
ad
H

20. i
i d
ad
H

21. i
i d
ad
H

22. i
i d
ad
H
User Part (UP)
Message Transfer Part (MTP)
OSI






23. i
i d
ad
H
MTP1
MTP3
MTP2
M
T
P
MTP1
OSI
Physical Layer


E-1(32*64Kbps)
DS-1(24*64Kbps)
V35(64Kbps)
DS-0(64Kbps)
DS-0A(56Kbps)







Digital Signal
Destination
DS0
DS1
DS1C
DS2
DS3
DS3
Bandwidth
64 kbps
1.544 mbps
3.152 mbps
6.312 mbps
44.736 mbps
274.176 mbps
Channels
(DS0s)
1 channel
24 channels
48 channels
96 channels
672 channels
4032 channels
Carrier
Designation
None
T-1
T-1c
T-2
T-3
T-4

24. i
i d
ad
H
MTP3
MTP2
M
T
P
MTP2
MTP1
OSI
(Data Link)

Signaling Unit




(SU)







(Flow Control)
(Sequence Validation)



25. i
i d
ad
H
FISU
MSU
LSSU
ACK
FISU
LSSU MSU







MTP


MTP2

26. i
i d
ad
H
Flag (F)




Backward Sequence Number (BSN)

Backward Indicator Bit (BIB)

Forward Sequence Number (FSN)

Forward Indicator Bit (FIB)

Length Indicator (LI)

LI
FCS

27. i
i d
ad
H
Signaling Information Field (SIF)
MSU

MTP
(Routing Label)
Destination point Code (DPC)
Origination point Code (OPC)
Signaling Link Selector (SLS)
SLS
MTP2






Overload

Share



28. i
i d
ad
H
SIO
Sub-Service Indicator
Service Indicator
Service Indicator Octet (SIO)
SI
MSU
MSU
Service Indicator (SI)
ID
MTP


MTP3
MTP
Sub-Service Indicator



29. i
i d
ad
H
Status Indicator (SI)
LSSU


LSSU
SIOS SIB SIO



30. i
i d
ad
H
SS7

FCS

FCS

X^16+X^12+X^5+1

FCS

MTP2
FCS
FCS
FCS
FCS





MTP2
Basic method
Preventive Cyclic Retransmision method



31. i
i d
ad
H
MTP3
MTP2
M
T
P
MTP3
MTP1
OSI
(Network)


MTP2





32. i
i d
ad
H
MTP3 Users
MTP3
Distribution
Function
MTP2
Discrimination
Function
SCCP
ISUP
etc
Routing
Function

DPC

MTP3
SIO

DPC
SLS



Overload

33. i
i d
ad
H





MTP





STP
STP
STP

STP STP

STP

STP
STP

34. i
i d
ad
H

35. i
i d
ad
H
ISUP

(Setup)


Non ISDN
(Release)
ISDN

ISUP

ISUP
CIC (Circuit Identification Code)


36. i
i d
ad
H
ISUP
IAM (Initial Address Message)

Called number, calling number, transmission requirement, type of •
caller, …
ACM (Address Complete Message)

The call is through-connected to the destination •
A one-way-audio path is opened for ring-back tone •
Optional •
If not returned, no ring-back tone at all 
CPG (Call Progress)

Optional; provide information to the calling switch •
ANM, Answer Message

Open the transmission path in both directions •
Instigate charging for the call •
REL (Release)
RLC (Release Complete)



37. i
i d
ad
H
SCCP
MTP3


Connectionless
Connection-oriented
Global Title Translation (GTT)




38. i
i d
ad
H
Connectionless





39. i
i d
ad
H
Connection-oriented


SCCP
Local Reference

SCCP



40. i
i d
ad
SCCP Users
H
MAP
OMAP
SCCP
MTP3
SCCP Connection-oriented
Control
(SCOC)
SCCP
Routing
Control
(SCRC)
HLR
VLR
SCCP
SCCP Connectionless
Control
(SCLC)
MSC
SCRC
MTP
EIR
SCCP management
(SCMC)
:
SCCP



:
SCOC
Connection-oriented


Segmentation

Sequencing
Flow control


SCLC
Connectionless

SCLC
SCCP
SCCP




SCCP



41. i
i d
ad
Optional
H
Parameters
Mandatory Variable
Parameters
Pointers
Mandatory Fixed
Parameters
Message
Type
Routing
Label
SCCP







EO
00


42. i
i d
ad
H
SCCP
CdPA , CaPA (>2Byte)
SPC (2 Bytes)
SSN (1 Byte)
Global Title (> 3 Bytes)




Credit (3Bytes)


Secured

SCCP
UnACK

End of optional parameters (1 Byte)
Message Type (1Byte)
Protocal class (1Byte)
0,1,2,3




43. i
i d
ad
H
SCCP
Release Cause (1Byte)
“0FHex”

SCCP Connection
Refusal Cause (1Byte)
Return cause (1Byte)
UDT
UDTS


UDTS
SLR/DLR (each 3 Bytes)
Segmenting /Reassembling (1Byte)
virtual connection


Local Reference
DT1
DT1
Sequencing /Segmenting (2 Bytes)
Segmentation
SCCP
MTP2
P(S) P(R)
BSN FSN
P(S) P(R)

IT DT2
S/R
Subsystem Number (1 Byte)
SCCP


44. i
i d
ad
H
SSN
SCCP
SCCP
SSN


SCCP

SSN


45. i
i d
ad
BSC
H
SCCP
MSC
CR
CC
DT1
SLR
CR

DT1
DT1
DT1
SLR
CC

DLR
:
:
DT1
DT1

RLSD
RLC
RLSD

RLC


46. i
i d
ad
H
A-Interface
MAP
BSSAP
Abis-Interface
Q931
SCCP
SCCP
MTP
HLR
TCAP
Air-Interface
MTP
Q931
Q921
LAPD
LAPDm
VLR
E1/T1
MSC
EIR
AC
SS7
E1/T1
BSC
BTS
E1/T1
Air

47. i
i d
ad
H
GSM protocol layers for signaling
Um
Abis
MS
BTS
A
BSC
MSC
CM
CM
MM
MM
RR
LAPDm
RR’
LAPDm
radio
radio
BTSM
LAPD
PCM
RR’
BTSM
LAPD
PCM
BSSAP
BSSAP
SS7
SS7
PCM
PCM

48. i
i d
ad
H
GSM
MS
SS
HLR
MM + CM
1
2
3
4
7
5
8
RR
6
9
0
MSC
VLR
#
BSC
BTS
Radio interface

49. i
i d
ad
H
A-Interface
TRAU
LAPD TS1
OAM
Uncompressed Speech TS
Compressed Speech TS
64 Kbps
BSC
64 Kbps
Transcoding
64 Kbps
64 Kbps
64 Kbps
CCS7 TS
X.25 TS2
PCM
LINK
MSC
CCS7 TS
X.25 TS2
PCM
LINK
OMC

50. i
i d
ad
H
A-Interface
TRAU
LAPD TS1
OAM
Uncompressed Speech TS
Compressed Speech TS
64 Kbps
BSC
64 Kbps
Transcoding
64 Kbps
64 Kbps
64 Kbps
CCS7 TS
X.25 TS2
PCM
LINK
MSC
CCS7 TS
X.25 TS2
PCM
LINK
OMC

51. i
i d
ad
H
BSSMAP
Data (BSSAP)
SCCP
Length (8 Bits)
0
0
0
0
0
0
0
1
DLCI
Byte-2
0
0
0
0
0
C
B
SAPI
A
DTAP (2 Bytes)
Byte-1
Header
0 --------->RR, MM, CC
3 --------->SMS, SS
BSSMAP (1 Byte)
RR
MSC
DTAP
BSC
MS
CC/MM
BSSAP
SCCP
0
0
0
0
0
0
0
0

52. i
i d
ad
H
BSSMAP
Data (BSSAP)
Parameter N
Parameter N-1
Parameter A
Optional Parameters
Parameter A
Parameter A
Mandatory Parameters
Data
Length
IEI
Message Type

53. i
i d
ad
H
DTAP
Data (BSSAP)
Parameter N
Parameter N-1
Optional Parameters
Data
Length
Data
IEI
IEI
Parameter A
Parameter A
Parameter A
Message Type
Mandatory Parameters
Optional Variable Length
Optional Fixed Length
Data
Data
Mandatory Fixed Length
Length
Mandatory Variable Length

54. i
i d
ad
H
HLR
EIR
TCAP
MSC VLR
TCAP
SCCP
Connectionless
MTP
(Applications)
(Queries)
SCP
SSP
MSC
MAP
Authentication, IMEI

SCCP
TCAP
(Responses)
TCAP
HLR
Checking, Roaming



55. i
i d
ad
H