%% You should probably cite rfc6337 instead of this I-D. @techreport{ietf-sipping-sip-offeranswer-18, number = {draft-ietf-sipping-sip-offeranswer-18}, type = {Internet-Draft}, institution = {Internet Engineering Task Force}, publisher = {Internet Engineering Task Force}, note = {Work in Progress}, url = {https://datatracker.ietf.org/doc/draft-ietf-sipping-sip-offeranswer/18/}, author = {Shinji OKUMURA and Takuya Sawada and Paul Kyzivat}, title = {{Session Initiation Protocol (SIP) Usage of the Offer/Answer Model}}, pagetotal = 33, year = 2011, month = jun, day = 5, abstract = {The Session Initiation Protocol (SIP) utilizes the offer/answer model to establish and update multimedia sessions using the Session Description Protocol (SDP). The description of the offer/answer model in SIP is dispersed across multiple RFCs. This document summarizes all the current usages of the offer/answer model in SIP communication. This document is not an Internet Standards Track specification; it is published for informational purposes.}, }