Common Channel Signaling System No. 7 (SS7, C7, No. 7) is a global standard for telecommunications, defined for use in public switched networks where large numbers of circuits are switched between subscribers. SS7 is a global standard used throughout the world within networks and on international interconnects; it is the signaling technology inside the network that delivers (Integrated Services Digital Network) ISDN, mobile/wireless and Intelligent Networking.

SS7 handles a wealth of functions, from basic call setup, management and tear down to advanced services like local number portability, toll-free ("800") services, call forwarding, caller ID and three-way calling. While SS7 was not specifically designed for wireless networks, its robust and versatile design was easily adapted to support mobile telephony services, such as PCS, wireless roaming and mobile subscriber authentication. Now the venerable protocol is being adapted to support the next generation of services in the converging circuit-switched and packet-switched network environment.

Following is a list of some products where SS7 has been successfully integrated:

  • 3G Nodes (UMTS) - RNC, SGSN, HLR
  • Voice over Packet - Gateways & Softswitches
  • Interworking products (e.g. SS7-ISDN interworking)
  • SMSC
  • Intelligent Peripherals, Service Node, SCP
  • Test and Measurement Tools (protocol testers)
  • Monitoring Tools
  • Wireline Trunk Switches