# SS7 - Signalling System No. 7 SS7 is used for signaling between networks. SS7 is a global standard for telecommunications that defines how network elements in a [[PSTN - Public Switched Telephone Network|PSTN]] exchange information over a digital signaling network. SS7 is essential for tasks like setting up and terminating phone calls, routing SMS messages, enabling mobile roaming, and handling other network functions such as call forwarding and billing. --- Bibliography: - [Locating Mobile Phones using Signalling System 7 - berlin.ccc.de](need bibliography)