Signaling System No. 7

By Lee Dryburgh and Jeff Hewett

• Table of Contents
  • Copyright
  • About the Authors
  • Acknowledgments
  • Icons Used in This Book
  • Command Syntax Conventions
  • Introduction
  • Part I. Introductions and Overviews
  • Chapter 1. The Evolution of Signaling
  • Chapter 2. Standards
  • Chapter 3. The Role of SS7
  • Chapter 4. SS7 Network Architecture and Protocols Introduction
  • Chapter 5. The Public Switched Telephone Network (PSTN)
  • Part II. Protocols Found in the Traditional SS7/C7 Stack
  • Chapter 6. Message Transfer Part 2 (MTP2)
  • Chapter 7. Message Transfer Part 3 (MTP3)
  • Chapter 8. ISDN User Part (ISUP)
  • Chapter 9. Signaling Connection Control Part (SCCP)
  • Chapter 10. Transaction Capabilities Application Part (TCAP)
    • Overview
    • Message Types
    • Transactions
    • Components
    • Dialogue Portion
    • Message Encoding
    • Element Structure
    • Error Handling
    • ITU Protocol Message Contents
    • ANSI Protocol Message Contents
    • ANSI National Operations
    • ANSI Parameters
    • Summary
  • Part III. Service-oriented Protocols
  • Chapter 11. Intelligent Networks (IN)
  • Chapter 12. Cellular Networks
  • Chapter 13. GSM and ANSI-41 Mobile Application Part (MAP)
  • Part IV. SS7/C7 Over IP
  • Chapter 14. SS7 in the Converged World
  • Part V. Supplementary Topics
  • Chapter 15. SS7 Security and Monitoring
  • Chapter 16. SS7 Testing
  • Part VI. Appendixes
  • Acronyms
  • Appendix A. MTP Messages (ANSI/ETSI/ITU)
  • Appendix B. ISUP Messages (ANSI/UK/ETSI/ITU-T)
  • Appendix C. SCCP Messages (ANSI/ETSI/ITU-T)
  • Appendix D. TCAP Messages and Components
  • Appendix E. ITU-T Q.931 Messages
  • Appendix F. GSM and ANSI MAP Operations
  • Appendix G. MTP Timers in ITU-T/ETSI/ANSI Applications
  • Appendix H. ISUP Timers for ANSI/ETSI/ITU-T Applications
  • Appendix I. GSM Mobile Country Codes (MCC) and Mobile Network Codes (MNC)
  • Appendix J. ITU and ANSI Protocol Comparison
  • Appendix K. SS7 Standards
  • Appendix L. Tektronix Supporting Traffic
  • Appendix M. Cause Values

ITU Protocol Message Contents

The definition of each message type indicates a set of fields that comprise the message. While some fields are mandatory, others are optional. As specified by Q.773, the standard set of ITU messages includes:

• Unidirectional
• Begin
• End
• Continue
• Abort

The following sections describe these messages, the fields that are included in each one, and indicate which fields are mandatory or optional.

Unidirectional Message

The Unidirectional Message is sent when no reply is expected. Table 10-9 lists the message contents.

Table 10-9. Unidirectional Message Fields

Unidirectional Message Fields	Mandatory/Optional
Message Type Total Message Length	Mandatory
Dialogue Portion	Optional
Component Portion Tag Component Portion Length	Mandatory
One or More Componnts	Mandatory

Begin Message

The Begin Message is sent to initiate a transaction. Table 10-10 lists the message contents.

Table 10-10. Begin Message Fields

Begin Message Fields	Mandatory/Optional
Message Type Total Message Length	Mandatory
Originating Transaction ID Tag Transaction ID Length Transaction ID	Mandatory
Dialogue Portion	Optional
Component Portion Tag Component Portion Length	Optional [*]
One or More Components	Optional

EndMessage

The End Message is sent to end a transaction. Table 10-11 lists the message contents.

Table 10-11. End Message Fields

End Message Fields	Mandatory/Optional
Message Type Total Message Length	Mandatory
Destination Transaction ID Tag Transaction ID Length Transaction ID	Mandator
Dialogue Portion	Optional
Component Portion Tag Component Portion Length	Optional [*]
One or More Components	Optional

Continue Message

The Continue Message is sent when a transaction has previously been established and additional information needs to be sent without ending the transaction. Table 10-12 lists the message contents.

Table 10-12. Continue Message Fields

Continue Message Fields	Mandatory/Optional
Message Type Total Message Length	Mandatory
Originating Transaction ID Tag Transaction ID Length Transaction ID	Mandatory
Destination Transaction ID Tag Transaction ID Length Transaction ID	Mandatory
Dialogue Portion	Optional
Component Portion Tag Component Portion Length	Optional [*]
One or More Components	Optional

Abort Message

The Abort Message is sent to terminate a previously established transaction. Table 10-13 lists the message contents.

Table 10-13. Abort Message Fields

Abort Message Fields	Mandatory/Optional
Message Type Total Message Length	Mandatory
Destination Transaction ID Tag Transaction ID Length Transaction ID	Mandatory
P-Abort Cause Tag P-Abort Cause Length P-Abort Cause	Optional [*]
Dialogue Portion	Optional

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