SS7 is a set of protocols allowing phone networks to exchange the information needed for passing calls and text messages between each other and to ensure correct billing. It also allows users on one network to roam on another, such as when travelling in a foreign country.

What protocol does SS7 use?

SS6 and SS7 are referred to as common-channel signaling (CCS) protocols, or Common Channel Interoffice Signaling (CCIS) systems. Another element of in-band signaling addressed by SS7 is network efficiency.

Is SS7 still in use?

During the early 1990s, the SS7-based software system was just coming into wide use. Today, though, it is considered outdated and insecure. Despite that, carriers still use the technology as a backup in their networks.