Session Initiation Protocol for Telephones (SIP-T): Context and Architectures

The popularity of gateways that interwork between the PSTN (Public Switched Telephone Network) and SIP networks has motivated the publication of a set ofcommon practices that can assure consistent behavior across implementations. This document taxonomizes the uses of PSTN-SIP gateways, provides uses cases, and identifies mechanisms necessary for interworking. The mechanisms detail how SIP provides for both 'encapsulation' (carriage of PSTN signaling across a SIP network) and 'translation' (protocol mapping).