A protocol used in the public switched telephone system (intelligent network) for setting up calls and providing services. The SS7 network sets up and tears down the call, handles all the routing decisions and supports all telephony services such as 800 numbers, call forwarding, caller ID and local number portability (LNP). The voice switches that carry the telephone conversations are known as "service switching points" (SSPs). The SSPs query "service control point" (SCP) databases using packet switches called "signal transfer points" (STPs).