%% You should probably cite rfc7433 instead of this I-D. @techreport{ietf-cuss-sip-uui-06, number = {draft-ietf-cuss-sip-uui-06}, 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-cuss-sip-uui/06/}, author = {Alan Johnston and James Rafferty}, title = {{A Mechanism for Transporting User to User Call Control Information in SIP}}, pagetotal = 18, year = 2012, month = may, day = 4, abstract = {There is a class of applications which benefit from using SIP to exchange User to User Information (UUI) data during session establishment. This information, known as call control UUI data, is a small piece of data inserted by an application initiating the session, and utilized by an application accepting the session. The rules which apply for a specific application are defined by a UUI package. This UUI data is opaque to SIP and its function is unrelated to any basic SIP function. This document defines a new SIP header field, User-to-User, to transport UUI data, along with an extension mechanism.}, }