Signalling System #7 General Overview Training

Signaling System #7 (SS7) (aka C7 outside N.America) is the predominant signalling system for the public switched telephone network (PSTN) and also Public Land Mobile Networks (PLMNs). New packet networks for voice telephony also typically rely on SS7 for signalling. SS7 defines the procedures for setting-up, managing and clearing down calls between users, as well as non-circuit related signaling. For example it is used to provide Local Number Portability (LNP) as mandated by the FCC, Call Management Database Services (CMSDB) such as 800, 900, and 500 services (0500,0800,0898 Etc within the UK), and Line Information Database Services (LIDB) such as calling card services. The SS7 protocol is also a key component in providing Advanced Intelligent Networks (AINs) as defined by Bellcore and Intelligent Networks as defined by ITU-T.


Training Method

  • Lectures
  • Exercises
  • Demonstrations

course details

  • Duration: One day
  • Language: English
  • Documentation: English
  • Participants: No limitations


The course has no prerequisites, although a technical understanding of voice networks and associated technology would be beneficial.

Learning Outcomes

  • Knowledge of C7/SS7 Architecture Including Signaling Points and Links
  • Ability to Define Signal Unit Structure
  • Knowledge of what Function MTP Performs
  • Knowledge of what Function the User Parts for Fixed Line Perform
  • Ability to Explain ISUP Message Format and Describe Basic Messages
  • Knowledge of what Function SCCP Performs Including SCCP Classes
  • Knowledge of what Function TCAP Performs
  • Knowledge of what an IN is and what the Associated Standards are
  • Knowledge of what the Wireless User Parts are and their functions

who should attend

  • Technical development and support professionals involved in the support and implementation of networks and services who wish to have a general appreciation of SS7 concepts and terminology
  • Planners and developers of packet based carrier grade networks and services that wish to have a basic grasp of the purpose of SS7 and associated terminology

Presenter Details

The course is delivered by Lee S Dryburgh lead author of Signaling System No. 7 (SS7/C7): Protocol, Architecture, and Services (Networking Technology).

What is Signaling?

  • What is Signaling?
  • The Purpose of Signaling Explained
  • Where does C7/SS7 Signaling Take Place?

SS7/C7 Network Elements

  • The Three Types of Signaling Point (SP) Explained
  • Links and Linksets Explained
  • The N. American SS7 Network Architecture Shown
  • The UK C7 Network Architecture Shown

SS7/C7 Overview

  • The C7/SS7 Protocol Stack compared with the OSI Model Shown
  • C7/SS7 Functionality Overviewed
  • Requirements of C7/SS7 Signaling
  • Advantages of C7/SS7 Signaling
  • Associated Mode
  • Quasi-Associated Mode
  • Who are the C7 and SS7 Protocol Standards Bodies?

Message Transfer Part 1 (MTP 1)

  • MTP 1 Overviewed

Message Transfer Part 2 (MTP 2)

  • MTP 2 Overviewed
  • Signal Units and the Three Types Explained
  • SU Layers of Operation Shown
  • MTP 2 Overhead Shown
  • SU Delimination Described
  • SU Error Detection/Correction Explained
  • Basic Error Correction Method Shown
  • Link Error Monitoring Described
  • Link Initial Alignment Shown

Message Transfer Part 3 (MTP 3)

  • Functions of MTP 3 Described?
  • MTP 3 Overhead Shown
  • Signaling Information Field (SIF) for MTP 3 MSUs Shown
  • Contents of Service Information Octet (SIO) Explained
  • Service Information Octet (SIO)- SubService Field (SSF) Shown
  • Service Information Octet (SIO)- Service Indicator (SI) Shown
  • The ITU Routing Label Described and Shown
  • The ANSI Routing Label Described and Shown
  • The UK Routing Label Described and Shown
  • International/National SS7/C7 Networks Hierarchy Explained
  • Relationship between L1, L2 and L3 Shown
  • Signaling Network Management (SNM) Overviewed
  • Signaling Message Handling (SMH) Overviewed
  • MTP Summarised

SS7/C7 Overview

  • The SS7/C7 Protocol Stack against the OSI Model
  • SS7/C7 Functionality Overview
  • SS7/C7 Based Services - CNAM, LNP, CLASS, LIDB, SMS, EMS, PVN, E911, Do-Not-Call, and Supplementary Services
  • SS7/C7 as Thread of Convergence

SS7/C7 Network Elements

  • Service Switching Point (SSP)
  • Signal Transfer Point (STP)
  • Service Control Point (SCP)
  • N. American SS7 Network Architecture
  • European and Asian C7 Network Architecture
  • Link Types and Usage
  • Links and Linksets Explained
  • Routes and Routesets Explained

Message Transfer Part 1 (MTP 1)

  • Functions of MTP 1 Described
  • North American T1 Carrier Explained
  • European PRI E1 Carrier Explained
  • The Digital TDM Hierarchy for N. America Shown
  • The Digital TDM Hierarchy for Europe and Asia Shown

Message Transfer Part 2 (MTP 2)

  • Functions of MTP 2 Described
  • MTP 2 Overhead Shown
  • Signal Units Introduced
  • Message Signal Unit (MSU) Detailed
  • Link Status Signal Unit (LSSU) Detailed
  • Fill in Signal Unit (FISU) Detailed
  • SU Layers of Operation Explained
  • SU Delimination Explained
  • SU Alignment Explained
  • SU Error Detection/Correction Explained
  • Basic Error Correction Method Shown
  • Preventive Cyclic Retransmission Shown
  • Methods used for Link Error Monitoring
  • Link Management Detailed
  • Link Transmission Priorities Shown
  • Link Initial Alignment Shown

Message Transfer Part 3 (MTP 3)

  • Functions of MTP 3 Described
  • MTP 3 Overhead and Message Format Shown
  • Service Information Octet (SIO) Contents Explained
  • SubService Field (SSF) Explained
  • Service Indicator (SI) Explained
  • ITU Routing Label Shown
  • ITU Point Code Format Explained
  • ANSI Routing Label Shown
  • ANSI Point Code Format Explained
  • Assignment of the ANSI Point Code Explained
  • UK Routing Label Shown
  • UK Point Code Format Explained
  • Assignment of UK, US and International Point Codes Explained
  • International and National SS7/C7 Network Hierarchy Explained
  • Point Codes and Interconnect Explained
  • Relationship between L1, L2 and L3 Shown
  • Signaling Message Handling (SMH) Overviewed
  • SMH - Routing in More Detail (SLS and CIC) Fields
  • SMH - Heading Code (H0 / H1) Fields
  • Signaling Network Management (SNM) Overviewed
  • Signaling Traffic Management (STM) Overviewed
  • STM - Changeover/Changeback Examples
  • STM - Forced and Controlled Re-Routing Examples
  • STM - MTP Restart Example
  • STM - Management Inhibiting Example
  • STM - Flow Control & Traffic Reconfiguration Example
  • Signaling Link Management (SLM) Overviewed
  • SLM - Link Activation Demonstrated
  • SLM - Restoration Demonstrated
  • SLM - De-Activation Demonstrated
  • Signaling Link Test Explained
  • Processor Outage Explained
  • Signaling Route Management Overviewed
  • SRM - Transfer Prohibited Example
  • SRM - Transfer Allowed Example
  • SRM - Route Set Test Example
  • MTP3b (Broadband) Described

Fixed Line User Parts

  • User Parts Described
  • TUP Overviewed
  • NUP/IUP Explained
  • Two NUP Call Sequences Shown
  • N-ISDN User Part (N-ISUP) Overviewed
  • Signaling Information Field (SIF) for N-ISUP MSU Shown
  • N-ISUP Evolution Explained
  • N-ISUP Variants Discussed
  • N-ISUP Message Groups Shown
  • Five N-ISUP Messages Explained/Shown
  • Two Call Sequences Shown
  • Supplementary Services Described

Signaling Connection Control Part (SCCP)

  • Signaling Connection Control Part (SCCP) Overviewed
  • Two Categories of Service and Four Protocol Classes Described
  • Connection Orientated Procedures Example
  • Connectionless Procedure Example

Intelligent Networks (INs)

  • Intelligent Networks (INs) Described
  • IN Standards Described

Transaction Capabilities Application Part (TCAP)

  • Transaction Capabilities Application Part (TCAP) Overviewed
  • TCAP Definitions Detailed
  • Components/Transactions Described
  • The Transaction Capabilities (TC) Described

Wireless User Parts

  • MAP Described
  • BSSAP Described
  • BSSMAP Described
  • DTAP Described

C7/SS7 Protocol Standards and Recommendations

  • C7 Protocol Standards - Europe/Britain Detailed
  • SS7 Protocol Standards - Europe/N. America Detailed


  • Appendix A - SS7/C7 Standards
  • Appendix B - Further Reading




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