%% You should probably cite rfc4964 instead of this I-D. @techreport{allen-sipping-poc-p-answer-state-header-05, number = {draft-allen-sipping-poc-p-answer-state-header-05}, type = {Internet-Draft}, institution = {Internet Engineering Task Force}, publisher = {Internet Engineering Task Force}, note = {Work in Progress}, url = {https://datatracker.ietf.org/doc/draft-allen-sipping-poc-p-answer-state-header/05/}, author = {Jan Holm and Andrew Allen and Thomas Hallin}, title = {{The P-Answer-State Header Extension to the Session Initiation Protocol for the Open Mobile Alliance Push to Talk over Cellular}}, pagetotal = 32, year = 2007, month = mar, day = 5, abstract = {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. This memo provides information for the Internet community.}, }