The P-Answer-State Header Extension to the Session Initiation Protocol for the Open Mobile Alliance Push-to-talk over Cellular

The P-Answer-State Header Extension to the Session Initiation Protocol for the Open Mobile Alliance Push-to-talk over Cellular This document describes a private Session Initiation Protocol(SIP) header (P-header) used by the Open Mobile Alliance (OMA), for Push- to-talk over Cellular (PoC) along with its applicability, which is limited to the OMA PoC application. The P-Answer-State header is used for indicating the answering mode of the handset which is particular to the PoC application.