The Presence-specific Dictionary for the Signaling Compression (Sigcomp) Framework
The Session Initiation Protocol (SIP) [4] is a text-based protocol for initiating and managing communication sessions. The protocol is extended by the SIP-events framework [5] to provide, e.g., subscriptions and notifications to presence information that are carried in presence documents [8]. SIP can be compressed by using Signaling Compression (SigComp) [2], which is enhanced by using the SIP/SDP dictionary [7] to achieve better compression rates. However, the SIP/SDP dictionary [7] is not able to increase the compression factor of (typically lengthy) presence documents. This memo defines the presence-specific static dictionary that SigComp may use in order to achieve higher efficiency. The dictionary is compression algorithm independent.