What Does Signaling System No.7 (SS7) Mean?
Signaling System No.7 (SS7) is a telecommunications signaling architecture traditionally used for the set up and tear down of telephone calls. It has a robust protocol stack that uses out-of-band signaling to communicate between elements of the public switched telephone network (PSTN). In recent years it has been superseded by the Diameter signaling protocol on all-IP networks.
Techopedia Explains Signaling System No.7 (SS7)
In the past all communication between elements of the PSTN took place on the same channel as telephone conversations. This was called “in-band signaling.” It became a problem when curious pranksters (including Steve Wozniak and Steve Jobs) discovered that they could emulate telecom signals and explore secret telecom codes using something called a “blue box.”
