TABLE OF CONTENTS The Moon begins where the sherry ends with the lemon
Andr Breton
SS7 was first specified in the 1979 1980 Yellow Book of the Consultative Committee on International Telegraphy and Telephony (CCITT), now known as the International Telecommunication Union-Telecommunications Standardization Sector (ITU-T). SS7 has been gradually developed to meet the increasing signaling requirements of new services developed in the 1980s and 1990s. This standard has been released in the ITU-T's red (1984), blue (1988) and white (1992) recommendations (Q700 series) [1 16]. The Q700 series defines the procedures and protocols by which network elements in the public switched telephone network (PSTN) exchange services over a digital channel, such as call forwarding, calling party number display, conference calls.
The standardization of the signaling network is primarily concerned with the bottom three layers of the OSI model. This is the purpose of SS7 protocol stack in which the message transfer part (MTP) and signaling connection control part (SCCP) cover the layers 1 through 3 of the OSI model. The SCCP protocol can be viewed as an extension of the MTP layers that deals mainly with the integration of intelligent nodes (as SCPs or HLRs, for example), which are usually located outside the traffic-handling machines. SCCP belongs to OSI layer 3 and was first specified in 1984 (Recommendations Q711 Q714 [1 4]). SCCP also supports the use of the SS7 network as an advanced packet switched network for direct communications between two network entities...
