%% You should probably cite rfc7434 instead of this I-D. @techreport{ietf-cuss-sip-uui-isdn-09, number = {draft-ietf-cuss-sip-uui-isdn-09}, 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-isdn/09/}, author = {Keith Drage and Alan Johnston}, title = {{Interworking ISDN Call Control User Information with SIP}}, pagetotal = 20, year = 2014, month = jul, day = 21, abstract = {The motivation and use cases for interworking and transporting ITU-T DSS1 User-user information element data in SIP are described in RFC 6567. As networks move to SIP, it is important that applications requiring this data can continue to function in SIP networks as well as the ability to interwork with this ISDN service for end-to-end transparency. This document defines a usage (a new package) of the User-to-User header field to enable interworking with this ISDN service. This document covers the interworking with both public ISDN and private ISDN capabilities, so the potential interworking with QSIG will also be addressed. The package is identified by a new value "isdn-uui" of the "purpose" header field parameter.}, }