Ss7 Tutorial

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Table of Contents
SS7 Tutorial ..................................................................................................................................... 1 SS7 Tutorial ................................................................................................................................. 3Overview................................................................................................................................... 3 SS7 Protocol Stack .................................................................................................................. 6 Message Transfer Part............................................................................................................. 8 ISDN UserPart....................................................................................................................... 13 Signaling Connection Control Part ......................................................................................... 20 Transaction Capabilities Application Part............................................................................... 21 Other SS7Information............................................................................................................ 23 Bibliography............................................................................................................................ 23

List of Figures
Figure 1. SS7 Signaling Points ....................................................................................................... 4 Figure2. SS7 Signaling Link Types................................................................................................ 5 Figure 3. The OSI Reference Model and the SS7 Protocol Stack ................................................. 6 Figure 4. SS7 Signal Units.............................................................................................................. 8 Figure 5. Message TypeLength Indicator Value(s)........................................................................ 9 Figure 6. Service Indicator Values................................................................................................ 11 Figure 7. ANSI vs. ITU-T SIO and SIF.......................................................................................... 12 Figure 8. Basic ISUPSignaling..................................................................................................... 14 Figure 9. ISUP Message Format .................................................................................................. 16 Figure 10. ANSI and ITU-T Initial Address Message (IAM) Format ............................................. 17 Figure 11. ANSI and ITU-T Address Complete Message (ACM)Format..................................... 18 Figure 12. ANSI and ITU-T Answer Message (ANM) Format ...................................................... 18 Figure 13. ANSI and ITU-T Release (REL) Message Format ...................................................... 19 Figure 14. ANSI and ITU-T Release Complete (RLC) Message Format ..................................... 19 Figure 15. SCCP MessageFormat............................................................................................... 21

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08/22/01

Performance Technologies, Inc.

www.pt.com

SS7 Tutorial
Overview
Common Channel Signaling System No. 7 (i.e., SS7 or C7) is a global standard for telecommunications defined by theInternational Telecommunication Union (ITU) Telecommunication Standardization Sector (ITU-T). The standard defines the procedures and protocol by which network elements in the public switched telephone network (PSTN) exchange information over a digital signaling network to effect wireless (cellular) and wireline call setup, routing and control. The ITU definition of SS7 allows for national variants such as...