Hi Holger,
I'm sorry for again making this more complex than neccessary. It's up to you whether you would like to go down that route, of course :)
I found the following specifications that relate to how existing classic GSM/3GPP call control is mapped to SIP and vice versa (unfortunately typically over BICC as intermediate, but BICC is closer to 04.08 CC). In the context of interoperability with IMS this might be worth investigating:
* 3GPP CS interworking with BICC/ISUP and SIP-I networks http://www.3gpp.org/DynaReport/29164.htm http://www.3gpp.org/DynaReport/WiCr--13033.htm heavily based on ITU-T Q.1912.5: SIP <-> BICC/ISUP interworking https://www.itu.int/rec/T-REC-Q.1912.5-200403-I/en
(and as a side-note, ITU-T has actually specified conformance testing procedures for SIP in Q.3946.x)
* NcSIP (SIP Between G-MSCs?) http://www.3gpp.org/DynaReport/29802.htm http://www.3gpp.org/DynaReport/WiCr--320018.htm http://www.3gpp.org/DynaReport/WiCr--360025.htm
On Sat, Feb 27, 2016 at 10:21:56AM +0100, Harald Welte wrote:
A high-level description seems to be offered in TS 23.284 (http://www.etsi.org/deliver/etsi_ts/123200_123299/123284/13.00.00_60/ts_1232...)
http://www.3gpp.org/DynaReport/WiCr--430001.htm contains a list of changes made to other 3GPP specs for LCLS support.
There's also a follow-up to that in http://www.3gpp.org/DynaReport/WiCr--440021.htm