A.2 Introduction
24.2373GPPIP Multimedia (IM) Core Network (CN) subsystem IP Multimedia Subsystem (IMS) service continuityRelease 17Stage 3TS
A.2.1 General
The signalling flows provided in this annex follow the methodology developed in 3GPP TS 24.228 [3].
A.2.2 Key required to interpret signalling flows
The key to interpret signalling flows specified in 3GPP TS 24.228 [3] subclauses 4.1 and 4.2 applies with the additions specified below:
– tel:+1-237-555-1111 represents the public user identity of SC UE A.
– tel:+1-237-555-2222 represents the public user identity of UE B.
– sip:sccas1.home1.net represents the Internet host of SCC AS.
– sip:pstops.transfer@sccas1.home1.net represents the PS to PS STI.
– sip:domain.xfer@sccas.home1.net representing the static STI.
– #### represents the contents in the headers are not shown and does not impact the implementation of the flows.
– sip:home1.net represents the home network domain name of the SC UE A.
– sip:additional.session.xfer@sccas.home1.net represents the additional transferred session SCC AS URI.
– sip:additional.session.xfer.pscssrvcc@sccas.home1.net represents the additional transferred session SCC AS URI for PS to CS SRVCC.
– tel:+1-237-888-9999 represents the STN-SR owned by ATCF.
– sip:reg@atcf.visited2.net;lr represents the ATCF URI for originating requests.
– sip:termsdgfdfwe@atcf.visited2.net represents the ATCF URI for terminating requests.
– sip:atcf.visited2.net represents the ATCF management URI.
– sip:sti-sr@atcf.visited2.net represents the STI-rSR owned by ATCF.
– sip:AUT-STI1@sccas.home1.net represents the ATU-STI for PS to CS SRVCC.
– sip:cs2ps@sccas1.home1.net represents the ATU-STI for CS to PS SRVCC.
– sip:termpdfjkghlj@msc123.visited2.net;lr represents the MSC URI for terminating requests.
– sip:msc123.visited2.net represents the MSC management URI.
– sip:eatf1.visit1.net represents the EATF URI.
– sip:ecscf.visit1.net represents the E-CSCF URI.
Each signalling flow table contains descriptions for headers where the content of the header is new to that signalling flow, as is already performed in 3GPP TS 24.228 [3].
However, 3GPP TS 24.228 [3] includes extensive descriptions for the contents of various headers following each of the tables representing the contents of the signalling flows. Where the operation of the header is identical to that shown in 3GPP TS 24.228 [3], then such text is not reproduced in the present document.
Additional text may also be found on the contents of headers within 3GPP TS 24.228 [3] in addition to the material shown in the present document.
In order to differentiate between messages for SIP and media, the notation in figure A.2-1 is used.
Figure A.2-1: Signalling flow notation
For the signalling flows for registration (see subclause A.3.3), where the UE is using NG-RAN (see 3GPP TS 23.501 [37]), the MME is an AMF.