How This Book Is Organized

Those who are new to the world of telecommunications signaling should read Chapters 1 to 5 first, in sequence. Those who are already comfortable with telecommunications and signaling concepts can read particular chapters of interest. This book should prove the most valuable for those who already consider themselves experts in SS7/C7; in particular, attention should be given to the extensive appendixes.

Part I: Introductions and Overviews

Chapter 1: The Evolution of Signaling

This chapter introduces the concept of signaling. It is a great starting point for those who are unfamiliar with signaling or telecommunications in general. It introduces concepts and terminology that are used throughout the book.

Chapter 2: Standards

This chapter introduces the relevant standards and the bodies that are involved in creating them. It also provides some background on both the history of the standards and the bodies themselves. In addition, it introduces the concept of standards on different planes—national, regional, and international.

Chapter 3: The Role of SS7

This chapter is an excellent introduction to SS7/C7 and its relevance. Any reader can read it, regardless of background. Hopefully even those who are very knowledgeable in SS7/C7 will find this chapter interesting, because it lists the functions and services offered by SS7/C7 and explains its relevance in the daily lives of people across the globe.

Chapter 4: SS7 Network Architecture and Protocols Introduction

This chapter provides a technical overview of the SS7 protocol and network architecture. Those who are new to the subject will find it particularly interesting. It provides an introductory technical overview of SS7 in such a way that newcomers can assimilate subsequent chapters more effectively.

Chapter 5: The Public Switched Telephone Network (PSTN)

This chapter provides a brief overview of the Public Switched Telephone Network. It helps you understand SS7 in its native environment as the primary form of interoffice signaling in the PSTN. It also briefly introduces the PSTN's transition to the next-generation Voice Over Packet architecture.

Part II: Protocols Found in the Traditional SS7/C7 Stack

Chapter 6: Message Transfer Part 2 (MTP2)

This chapter examines the first protocol on top of the physical layer. It covers frame format, functions, and procedures—packet delineation, error correction, error detection, alignment, managing the signaling link, procedures for establishing a signaling link, flow control, and link error monitoring.

Chapter 7: Message Transfer Part 3 (MTP3)

This chapter covers the core concepts of how SS7 network nodes communicate with each other. It discusses network addressing and routing in detail, along with examples of how messages flow through an SS7 node. It also explains the numerous messages and procedures that MTP3 uses to maintain a healthy network.

Chapter 8: ISDN User Part (ISUP)

This chapter explains how the ISUP portion of the protocol is used to set up and tear down calls, provide trunk maintenance functions, and deliver supplementary services. It defines ISUP message structure as well as the most commonly used messages and parameters. The association between call processing at an SSP and the ISUP protocol is described, thereby helping you understand how an SS7-signaled call is processed at an SSP.

Chapter 9: Signaling Connection Control Part (SCCP)

This chapter looks at the enhanced functionality that the addition of this protocol brings—namely, application management, more flexible and powerful routing through the use of global titles, and mechanisms for transferring application data over the signaling network.

Chapter 10: Transaction Capabilities Application Part (TCAP)

This chapter describes the role of TCAP in providing a generic protocol mechanism for transferring information components between applications across the network. It helps you understand the key role TCAP plays in communication between SSP and SCP nodes. TCAP message formats and component definitions, including ITU and ANSI formats, are explained.

Part III: Service-Oriented Protocols

Chapter 11: Intelligent Networks (IN)

This chapter explains the concept of the Intelligent Network, how it has evolved, and how it is used to implement telecommunications services. It provides a detailed explanation of the IN call model and explains the parallels and differences between the ITU CS model and the North American AIN model. Several examples of IN services, such as toll-free calling and local number portability, are included to show how IN services are used.

Chapter 12: Cellular Networks

This chapter introduces GSM public land mobile networks (PLMNs) so that the following chapter can cover additional SS7 protocols used in cellular networks. It introduces cellular network entities, addressing, terminology, and concepts.

Chapter 13: GSM and ANSI-41 Mobile Application Part (MAP)

This chapter explains the operations and associated procedures that allow cellular subscribers to have mobility; this is the key functionality expected of a cellular network. Subscriber authentication, operations and maintenance, supplementary service, unstructured supplementary service (USS), and short message service (SMS) operations and procedures are also detailed.

Part IV: SS7/C7 Over IP

Chapter 14: SS7 in the Converged World

This chapter introduces the next-generation network architecture using media gateway controllers, media gateways, and signaling gateways. Its primary purpose is to provide an in-depth look at the Signaling Transport protocol (Sigtran), used between the media gateway controller and the signaling gateway. Sigtran is particularly interesting to those who are learning about SS7, because it provides a common signaling protocol interface between legacy SS7 networks and voice over IP networks.

Part V: Supplementary Topics

Chapter 15: SS7 Security and Monitoring

This chapter explains the need for SS7/C7 security practices. It describes the current means of providing security: traffic screening and monitoring. Details of providing traffic screening are supplied. Monitoring functionality and what should be monitored also are covered.

Chapter 16: SS7 Testing

This chapter explains the tools used for SS7/C7 protocol verification and how to create appropriate test specifications. It also outlines sample test cases for each protocol layer.

Part VI: Appendixes

Appendix A: MTP Messages (ANSI/ETSI/ITU)

This appendix lists all of the messages used by MTP3 for ANSI- and ITU-based networks. It also lists the message codes.

Appendix B: ISUP Messages (ANSI/UK/ETSI/ITU-T)

This appendix lists all of the messages used by ISUP for ANSI- and ITU-based networks. It also lists the message codes.

Appendix C: SCCP Messages (ANSI/ETSI/ITU-T)

This appendix lists all of the messages used by SCCP for ANSI- and ITU-based networks. It also lists the message codes.

Appendix D: TCAP Messages and Components

This appendix lists all of the messages and components used by MTP3 for ANSI- and ITU-based networks. It also lists the message codes.

Appendix E: ITU-T Q.931 Messages

Q.931 is the Layer 3 protocol of the subscriber signaling system that is used for ISDN, known as Digital Subscriber Signaling System No. 1 (DSS 1). It employs a message set that is made for interworking with SS7's ISUP. This appendix lists and describes the purpose of the Q.931 message set.

Appendix F: GSM and ANSI MAP Operations

This appendix lists the operations found in GSM MAP and their respective codes.

Appendix G: MTP Timers in ITU-T/ETSI/ANSI Applications

This appendix lists ANSI- and ITU-specified MTP timers.

Appendix H: ISUP Timers for ANSI/ETSI/ITU-T Applications

This appendix lists ANSI- and ITU-specified ISUP timers.

Appendix I: GSM Mobile Country Codes (MCC) and Mobile Network Codes (MNC)

This appendix lists all of the MCC codes and the respective MNCs found against the MCC.

Appendix J: ITU and ANSI Protocol Comparison

This appendix covers some of the main differences between ANSI and ITU (international).

Appendix K: SS7 Standards

This appendix presents the main SS7 standards alongside the respective standards body.

Appendix L: Tektronix Supporting Traffic

This appendix contains reference traffic caught on a Tektronix K1297 protocol analyzer.

Appendix M: Cause Values

Cause values, which are included as a field in each ISUP REL message, indicate why a call was released. This appendix lists and defines the ITU-T and ANSI cause values.