C.3 ATCF in architectures with Mx as a roaming interface without media anchored in ATGW
23.2373GPPIP Multimedia Subsystem (IMS) Service ContinuityRelease 17Stage 2TS
This clause describes the case when the P-CSCF and the ATCF are in the HPLMN in architectures without IMS-level roaming interfaces. In this clause there is no media anchoring in the ATGW. It can be seen that SIP signalling is transported from the MSC server in the VPLMN to the IBCF in the VPLMN via the Mx reference point and in the HPLMN from the IBCF to the ATCF via the Mx reference point as well.
Figure C.3-1: PS to CS access transfer
1. Interaction between UE, RAN, MME/SGSN and MSC Server as specified in TS 23.216 [10]. The following step is triggered after the MSC Server has received the PS to CS request from the MME / SGSN and has allocated resources in the RAN.
2. The MSC Server initiates Access Transfer message and if supported, the MSC Server indicates its capability to support MSC Server assisted mid-call feature. The MSC Server provides all the supported Codecs for voice or voice and video in the Access Transfer message. The Access Transfer message is sent to the IBCF in the VPLMN towards the IBCF in the HPLMN.
NOTE 1: The STN-SR received by the MSC server, in conjunction with the routing tables in the MSC server ensures the proper routing of SIP signalling from the VPLMN to the HPLMN towards the ATCF via the IBCF.
3. The IBCF in the HPLMN sends the Access transfer message via the Mx reference point to the ATCF. The ATCF receives the Access Transfer message and correlates the transferred session using the C-MSISDN. As the media flow has not been anchored in the ATGW, the ATCF forwards the Access Transfer message along with priority indication if received to the SCC AS using the stored ATU-STI. If the MSC Server indicated it supported mid-call feature, it also indicates this in the message to the SCC AS.
4. The SCC AS correlates the incoming Access Transfer message. As the Session Description has changed, a remote end update is initiated according to clause 6.3.1.5.
5. The SCC AS sends an Access Transfer response to the ATCF in the HPLMN. In the case MSC Server assisted mid-call feature is supported and used, the SCC AS provides Session State Information (SSI) according to clause 6.3.2.1.4a.
6. The ATCF forwards the response to the IBCF in the HPLMN and from there to the IBCF in the visited network.
7. The IBCF in the VPLMN forwards the response to the MSC Server. If the MSC Server receives the Session State Information of more than one active or inactive speech sessions, it initiates Access Transfer towards SCC AS for the additional session according to clause 6.3.2.1.4a.
NOTE 2: The success of mid-call features depends upon the proper transport of the SIP signalling towards the ATCF and the support in ATCF.
8. Procedures according to clause 6.3.2.1.4, steps 4a and 4b are used to handle the cases where the Gm reference point is either retained upon PS handover procedure, not retained upon PS handover, or if there was no other media flow(s) in the IMS session.
Annex D (informative):
Change history
|
Change history |
|||||||
|
Date |
Meeting |
TDoc |
CR |
Rev |
Cat |
Subject/Comment |
New version |
|
2011-03 |
SP-51 |
SP-110075 |
0347 |
4 |
F |
UE SRVCC capability support with ATCF enhancements |
10.5.0 |
|
2011-03 |
SP-51 |
SP-110075 |
0348 |
1 |
F |
Reference correction in clause 6.3.2.1.4 |
10.5.0 |
|
2011-03 |
SP-51 |
SP-110075 |
0352 |
1 |
F |
Correcting the IP address change behaviour |
10.5.0 |
|
2011-03 |
SP-51 |
SP-110075 |
0353 |
– |
F |
Editor’s note cleanup |
10.5.0 |
|
2011-03 |
SP-51 |
SP-110075 |
0354 |
– |
F |
ATGW transcoding support clarification |
10.5.0 |
|
2011-03 |
SP-51 |
SP-110069 |
0358 |
1 |
F |
IUT authorization by the SCC AS |
10.5.0 |
|
2011-03 |
SP-51 |
SP-110069 |
0359 |
1 |
F |
Check of service profile during IUT without establishing a Collaborative Session |
10.5.0 |
|
2011-03 |
SP-51 |
SP-110063 |
0363 |
2 |
A |
Correction to correlation of charging information collected at the MSC for SRVCC in roaming scenarios |
10.5.0 |
|
2011-03 |
SP-51 |
SP-110081 |
0361 |
3 |
B |
PS-CS Single Radio Access transfer for vSRVCC |
11.0.0 |
|
2011-06 |
SP-52 |
SP-110342 |
0366 |
1 |
F |
Remove editor’s note for alerting in case of vSRVCC |
11.1.0 |
|
2011-06 |
SP-52 |
SP-110342 |
0367 |
2 |
F |
Remove editor’s note on end-to-end video codec negotiation in case of vSRVCC |
11.1.0 |
|
2011-06 |
SP-52 |
SP-110337 |
0370 |
1 |
A |
Correction of Access Transfer Information handling for ATCF |
11.1.0 |
|
2011-06 |
SP-52 |
SP-110329 |
0376 |
– |
A |
Correction on Controllee UE Role |
11.1.0 |
|
2011-06 |
SP-52 |
SP-110329 |
0378 |
– |
A |
Correction on Remote Leg Update for IUT |
11.1.0 |
|
2011-06 |
SP-52 |
SP-110329 |
0380 |
1 |
A |
Clarification on Controller UE initiated media transfer from Controllee UE to another Controllee UE |
11.1.0 |
|
2011-06 |
SP-52 |
SP-110329 |
0382 |
1 |
A |
Correction and Clarification on Controllee UE initiated add new media on another Controllee UE |
11.1.0 |
|
2011-06 |
SP-52 |
SP-110329 |
0384 |
– |
A |
Correction and Clarification on pull mode media transfer (same IMS subscription) |
11.1.0 |
|
2011-09 |
SP-53 |
SP-110461 |
0391 |
2 |
A |
Update of retrieval of C-MSISDN |
11.2.0 |
|
2011-09 |
SP-53 |
SP-110461 |
0395 |
1 |
A |
Update of SIP message routeing due to AS PSI |
11.2.0 |
|
2011-09 |
SP-53 |
SP-110461 |
0399 |
2 |
A |
ATGW co-location clarification |
11.2.0 |
|
2011-09 |
SP-53 |
SP-110461 |
0403 |
– |
A |
Clarification to SRVCC of the session in pre-alerting state |
11.2.0 |
|
2011-09 |
SP-53 |
SP-110464 |
0400 |
1 |
B |
eMPS for SRVCC on IMS level |
11.2.0 |
|
2011-12 |
SP-54 |
SP-110737 |
0413 |
1 |
A |
Source access leg release for IMS emergency sessions |
11.3.0 |
|
2011-12 |
SP-54 |
SP-110737 |
0415 |
2 |
A |
Update on interface reference between ATCF and ATGW and reference index alignment |
11.3.0 |
|
2011-12 |
SP-54 |
SP-110745 |
0404 |
1 |
F |
Clarification of predefined codecs and PS to CS transfer of speech and video |
11.3.0 |
|
2011-12 |
SP-54 |
SP-110745 |
0405 |
– |
F |
Clarification of PS to CS transfer of speech and video in case of vSRVCC |
11.3.0 |
|
2011-12 |
SP-54 |
SP-110747 |
0407 |
2 |
B |
Introduction of SRVCC from CS to PS |
11.3.0 |
|
2011-12 |
SP-54 |
SP-110740 |
0411 |
1 |
B |
Clarification of emergency for SRVCC when using non-voice media |
11.3.0 |
|
2011-12 |
SP-54 |
SP-110748 |
0417 |
2 |
B |
Requirements for IUT remote end privacy preferences |
11.3.0 |
|
2011-12 |
SP-54 |
SP-110748 |
0418 |
1 |
F |
Clarification of the Source Access Leg Release procedure |
11.3.0 |
|
2012-03 |
SP-55 |
SP-120075 |
0424 |
1 |
A |
Removal of Instance ID in Session Transfer INVITE for SRVCC in alerting state |
11.4.0 |
|
2012-03 |
SP-55 |
SP-120088 |
0420 |
1 |
F |
PS to CS Dual Radio Access Transfer |
11.4.0 |
|
2012-03 |
SP-55 |
SP-120088 |
0421 |
1 |
F |
UE using ICS Capabilities in case of PS-CS Access Transfer |
11.4.0 |
|
2012-03 |
SP-55 |
SP-120084 |
0422 |
– |
F |
Clarification on the media gateway between PGW/GGSN and ATGW. |
11.4.0 |
|
2012-03 |
SP-55 |
SP-120084 |
0425 |
1 |
C |
Emergency call handling in rSRVCC |
11.4.0 |
|
2012-06 |
SP-56 |
SP-120242 |
0416 |
2 |
C |
Clarification on eMPS SRVCC |
11.5.0 |
|
2012-06 |
SP-56 |
SP-120250 |
0426 |
2 |
F |
Single Radio and Dual Radio clarification |
11.5.0 |
|
2012-06 |
SP-56 |
SP-120248 |
0427 |
3 |
F |
Providing rSRVCC capability in IMS layer |
11.5.0 |
|
2012-06 |
SP-56 |
SP-120245 |
0428 |
2 |
F |
Clarification on vSRVCC additional call transfer |
11.5.0 |
|
2012-06 |
SP-56 |
SP-120248 |
0429 |
– |
F |
ATU-STI alignments and corrections |
11.5.0 |
|
2012-06 |
SP-56 |
SP-120250 |
0432 |
2 |
F |
Single Radio and Dual Radio applicability |
11.5.0 |
|
2012-06 |
SP-56 |
SP-120253 |
0431 |
1 |
B |
Alerting for DRVCC |
12.0.0 |
|
2012-12 |
SP-58 |
SP-120714 |
0439 |
1 |
A |
Correction of the requirements for I2 interface and SRVCC corrections |
12.1.0 |
|
2012-12 |
SP-58 |
SP-120728 |
0440 |
– |
C |
Dynamic STN for DRVCC |
12.1.0 |
|
2012-12 |
SP-58 |
SP-120728 |
0441 |
2 |
B |
Incoming alerting for DRVCC |
12.1.0 |
|
2012-12 |
SP-58 |
SP-120728 |
0444 |
4 |
B |
SRVCC before ringing (brSRVCC) |
12.1.0 |
|
2012-12 |
SP-58 |
SP-120714 |
0448 |
2 |
A |
Correction to avoid the ATCF’s STN-SR to be overwritten when a registration over I2 or non-3GPP access occurs |
12.1.0 |
|
2012-12 |
SP-58 |
SP-120715 |
0450 |
2 |
A |
Definition of the MSC Assisted Mid-call feature |
12.1.0 |
|
2012-12 |
SP-58 |
SP-120728 |
0453 |
1 |
C |
Alignment of pre-alerting between SRVCC and DRVCC |
12.1.0 |
|
2012-12 |
SP-58 |
SP-120726 |
0455 |
1 |
A |
Suppression of announcements by MSC Server |
12.1.0 |
|
2013-03 |
SP-59 |
SP-130087 |
0457 |
– |
A |
I2 registration for rSRVCC |
12.2.0 |
|
2013-06 |
SP-60 |
SP-130232 |
0458 |
– |
F |
Correcting PS-CS Dual Radio flow |
12.3.0 |
|
2013-06 |
SP-60 |
SP-130213 |
0461 |
– |
A |
Clarification on aSRVCC mid-call |
12.3.0 |
|
2013-06 |
SP-60 |
SP-130223 |
0463 |
1 |
A |
Clarification regarding conference call participants leaving the conference |
12.3.0 |
|
2013-09 |
SP-61 |
SP-130378 |
0467 |
1 |
A |
Correction of IMEI encoding |
12.4.0 |
|
2013-12 |
SP-62 |
SP-130533 |
0468 |
1 |
F |
Correction in the definition of Pre-alerting state |
12.5.0 |
|
2014-03 |
SP-63 |
SP-140111 |
0469 |
– |
F |
Voice + video media fallback to voice media in case of SRVCC in pre-alerting state or alerting phase |
12.6.0 |
|
2014-06 |
SP-64 |
SP-140249 |
0472 |
– |
A |
IP-CAN access when an existing IMS voice session |
12.7.0 |
|
2014-06 |
SP-64 |
SP-140252 |
0478 |
1 |
A |
Select held session as the first transferred session for alerting + held session scenario with Mid-call feature |
12.7.0 |
|
2014-12 |
SP-66 |
SP-140686 |
0480 |
1 |
F |
Subscription for conference event package after SRVCC |
12.8.0 |
|
2015-06 |
SP-68 |
SP-150230 |
0483 |
1 |
F |
Enhanced MSC Server announcement during Session Transfer |
12.9.0 |
|
2015-06 |
SP-68 |
SP-150239 |
0481 |
1 |
F |
Notify UE conference event package after SRVCC |
13.0.0 |
|
2015-12 |
SP-70 |
SP-150599 |
0487 |
1 |
A |
Held session is being transferred first for alerting + held sessions scenario |
13.1.0 |
|
2016-06 |
SP-72 |
SP-160302 |
0488 |
3 |
B |
WLAN to CS session continuity for Emergency call over WLAN |
14.0.0 |
|
2016-09 |
SP-73 |
SP-160660 |
0489 |
2 |
B |
Robust Call Setup for VoLTE subscriber in LTE |
14.1.0 |
|
2016-09 |
SP-73 |
SP-160647 |
0494 |
2 |
F |
Support of SRVCC for eCall Over IMS |
14.1.0 |
|
2016-09 |
SP-73 |
SP-160658 |
0496 |
2 |
B |
SRVCC transcoding minimization |
14.1.0 |
|
2016-09 |
SP-73 |
SP-160654 |
0497 |
1 |
B |
Adding IMS emergency registration after SRVCC |
14.1.0 |
|
2016-12 |
SP-74 |
SP-160824 |
0498 |
1 |
F |
Robust Call Setup for VoLTE subscriber in LTE |
14.2.0 |
|
2016-12 |
SP-74 |
SP-160817 |
0499 |
– |
F |
DRVCC for emergency call with S2a/S2b only |
14.2.0 |
|
2017-09 |
SP-77 |
SP-170732 |
0504 |
1 |
B |
PS to CS SRVCC for IMS emergency session in early dialogue phase |
15.0.0 |
|
2017-12 |
SP-78 |
SP-170924 |
0503 |
4 |
B |
Support of bSRVCC on terminating side |
15.1.0 |
|
2018-06 |
SP-80 |
SP-180499 |
0506 |
– |
B |
Include support for eSRVCC in IMS architectures with no IMS-level roaming agreements |
16.0.0 |
|
2019-03 |
SP-83 |
SP-190162 |
0507 |
2 |
B |
Adding UDM update the STN-SR to AMF |
16.1.0 |
|
2019-06 |
SP-84 |
SP-190406 |
0509 |
2 |
B |
Introduction of support of multiple EATF instances in Emergency SRVCC procedures |
16.2.0 |
|
2019-06 |
SP-84 |
SP-190411 |
0510 |
2 |
F |
Completing introducing of 5G SRVCC |
16.2.0 |
|
2019-09 |
SP-85 |
SP-190601 |
0512 |
2 |
A |
Enabling SRVCC for emergency call transferred to EPS |
16.3.0 |
|
2020-07 |
SP-88E |
SP-200552 |
0514 |
1 |
F |
Corrections on ATCF |
16.4.0 |
|
2022-03 |
SP-95E |
– |
– |
– |
– |
Update to Rel-17 version (MCC) |
17.0.0 |