Tutorial on Signaling System 7 (SS7)

Tutorial on Signaling System 7 (SS7) pdf

Common Channel Signaling System No. 7 (SS7 or C7) is a global standard for telecommunications
defined by the International 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 North America’s American National Standards Institute (ANSI) and Bell
Communications Research (Telcordia Technologies) standards and Europe’s European
Telecommunications Standards Institute (ETSI) standard.
The SS7 network and protocol are used for:
• Basic call setup, management and tear down
• Wireless services such as personal communications services (PCS), wireless roaming and
mobile subscriber authentication
• Local number portability (LNP)
• Toll-free (800/888) and toll (900) wireline services
• Enhanced call features such as call forwarding, calling party name/number display and three-way
calling
• Efficient and secure worldwide telecommunications