A.1 CCBS activation and CCBS call

24.6423GPPCompletion of Communications to Busy Subscriber (CCBS) and Completion of Communications by No Reply (CCNR) using IP Multimedia (IM) Core Network (CN) subsystemProtocol specificationRelease 16TS

Figure A.1.1: CCBS activation and CCBS call

Figure A.1.1 shows a basic signalling flow for a CCBS activation and a CCBS call.

Call flows

1 to 5: The communication is initiated by UE-A by sending an INVITE request. The Request-URI will include the URI of UE-B. After IFC evaluation in the S-CSCF the INVITE request is routed to the originating AS and after that to the terminating AS and further on to UE-B.

Table A.1-1: SIP INVITE request (UE to P-CSCF)

INVITE sip:user2_public2@home2.net SIP/2.0

Via: SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp;branch=z9hG4bKnashds7

Max-Forwards: 70

Route: sip:pcscf1.home1.net:7531;lr;comp=sigcomp>, <sip:orig@scscf1.home1.net;lr>

Accept-Contact: *;+g.3gpp.icsi-ref="urn%3Aurn-7%3gpp-service.ims.icsi.mmtel"

Privacy: none

From: <sip:user1_public1@home1.net>; tag=171828

To: <sip:user2_public2@home2.net>

Call-ID: cb03a0s09a2sdfglkj490333

CSeq: 127 INVITE

Supported: 100rel; precondition, gruu, 199

Require: sec-agree

Contact: <sip:user1_public1@home1.net;gr=urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6>;+g.3gpp.icsi-ref="urn%3Aurn-7%3gpp-service.ims.icsi.mmtel"

Allow: INVITE, ACK, CANCEL, BYE, PRACK, UPDATE, INFO, REFER

Accept: application/sdp,application/3gpp-ims+xml

Content-Type: application/sdp

Content-Length: (…)

v=0

o=- 2987933615 2987933615 IN IP6 5555::aaa:bbb:ccc:ddd

s=-

c=IN IP6 5555::aaa:bbb:ccc:ddd

t=0 0

m=video 3400 RTP/AVP 98 99

b=AS:75

a=curr:qos local none

a=curr:qos remote none

a=des:qos mandatory local sendrecv

a=des:qos none remote sendrecv

a=inactive

a=rtpmap:98 H263

a=fmtp:98 profile-level-id=0

a=rtpmap:99:MPVMP4V-ES

m=audio 3456 RTP/AVP 97 96

b=AS:25.4

a=curr:qos local none

a=curr:qos remote none

a=des:qos mandatory local sendrecv

a=des:qos none remote sendrecv

a=inactive

a=rtpmap:97 AMR

a=fmtp:97 mode-set=0,2,5,7; maxframes=2

a=rtpmap:96 telephone-event

6: UE-B answers with a 486 (Busy Here) response. The 486 (Busy Here) response is routed back to the terminating AS.

7 to 8: The terminating AS inserts a Call-Info header field in the 486 (Busy Here) response according to the procedures described in RFC 6910 [5]. The Call-Info header field will contain the URI of the terminating AS with an "m" header field parameter set to "BS" (busy subscriber). It further includes a "purpose" header field parameters set to "call-completion". The 486 (Busy Here) response is routed back to the originating AS.

Table A.1-2: 486 (Busy Here) response (Terminating AS to S-CSCF))

SIP/2.0 486 Busy Here

Via: SIP/2.0/UDP tas.home2.net;branch= z9hG4bK332b23.1, SIP/2.0/UDP scscf2.home2.net;branch=z9hG4bK344a65.1, SIP/2.0/UDP icscf2_s.home2.net;branch=z9hG4bKj5hgrt2o, SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bKehuehjgt, SIP/2.0/UDP oas.home1.net;branch=z9hG4bKnashds7, SIP/2.0/UDP pcscf1.visited1.net;branch=z9hG4bK240f34.1, [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp;branch=z9hG4bKnashds7

From: <sip:user1_public1@home1.net>;tag=171828

To: <sip:user2_public2@home2.net>;tag=314159

Call-ID: cb03a0s09a2sdfglkj490333

CSeq: 127 INVITE

Retry-After: 3600

Contact: <sip:user2_public2@visited2.net;gr=urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91ewxyz>;+g.3gpp.icsi-ref="urn%3Aurn-7%3gpp-service.ims.icsi.mmtel"

Content-Length: 0

Call-Info:<sip:tas.home2.net>;purpose=call-completion;m=BS

9 to 10: The originating AS sends back a 183 (Session Progress) response to UE-A and initiates IVR procedures. User A is informed that CCBS is possible. User A activates CCBS.

11 to 12: The originating AS subscribes for the call-completion event package according to the procedures described in RFC 6910 [5] at the terminating AS. The originating AS generates a SUBSCRIBE request which Request-URI will include the URI of the terminating AS. In order to mark the SUBSCRIBE request as a request for CCBS, the originating AS adds the "m" SIP URI parameter with the value "BS" to the Request-URI. The From header field will include the caller URI. The To header field will include the callee URI.

Table A.1-3: SUBSCRIBE request (Originating AS to S-CSCF)

SUBSCRIBE sip:tas.home2.net;m=BS SIP/2.0

Via: SIP/2.0/UDP oas.home1.net;branch=z9hG4bKnashds7

Max-Forwards: 70

Route: <sip:scscf1.home1.net>

P-Asserted-Identity: <sip: user1_public1@home1.net>

From: <sip:user1_public1@home1.net>;tag=31415

To: <sip:user2_public2@home2.net>

Call-ID: b89rjhnedlrfjflslj40a222

Call-Info:<sip:user1_public1@home1.net>;purpose=call-completion;m=BS

CSeq: 61 SUBSCRIBE

Event: call-completion

Expires: 2700

Contact: <sip:oas.home1.net>

Content-Length: 0

13 to 14 The terminating AS accepts the subscription and starts busy state supervision procedures on the callee.

Table A.1-4: 200 (OK) response (Terminating AS to S-CSCF)

SIP/2.0 200 OK

Via: SIP/2.0/UDP scscf2.home2.net;branch=z9hG4bK344a65.1, SIP/2.0/UDP icscf2_s.home2.net;branch=z9hG4bKj5hgrt2o, SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bKehuehjgt, SIP/2.0/UDP oas.home1.net;branch=z9hG4bKnashds7

Record-Route:

From:

To: <sip:user2_public2@home2.net>;tag=151170

Call-ID:

CSeq:

Event:

Expires: 2700

Contact: <sip:tas.home2.net>

Content-Length:

15 to 18: The terminating AS sends a notification to the originating AS, according to the procedures described in RFC 6910 [5]. The Request-URI of the NOTIFY request will include the URI of the originating AS. The body contains parameters informing of the caller’s call-completion state ‘queued’ and the availability of the call-completion service retention at the terminating AS. After confirmation of the notification the originating AS starts announcements procedures informing about the activation of CCBS.

Table A.1-5: NOTIFY request (Terminating AS to S-CSCF)

NOTIFY sip:oas.home1.net SIP/2.0

Via: SIP/2.0/UDP tas.home2.net;branch=z9hG4bK348923.1

Max-Forwards: 70

Route: <sip:scscf2.home2.net>

P-Asserted-Identity: <sip:tas.home2.net>

From: <sip:user2_public2@home2.net>;tag=151170

To: <sip:user1_public1@home1.net>;tag=31415

Call-ID: b89rjhnedlrfjflslj40a222

CSeq: 42 NOTIFY

Subscription-State: active ;expires=2699

Event: call-completion

Contact: <sip:tas.home2.net>

Content-Type: application/call-completion

Content-Length: (…)

cc-state: queued

cc-service retention

19 to 20: The originating AS forwards the 486 (Busy Here) response to UE-A.

21 to 24: The terminating AS sends a NOTIFY request to the originating AS, according to the procedures described in RFC 6910 [5]. The body contains a parameter informing of the caller’s call-completion state ‘ready’ (for recall). The originating AS confirms the notification.

Table A.1-6: NOTIFY request (Terminating AS to S-CSCF)

NOTIFY sip:oas.home1.net SIP/2.0

Via: SIP/2.0/UDP tas.home2.net;branch=z9hG4bK348923.1

Max-Forwards: 70

Route: <sip:scscf2.home2.net>

P-Asserted-Identity: <sip:tas.home2.net>

From: <sip:user2_public2@home2.net>;tag=151170

To: <sip:user1_public1@home1.net>;tag=31415

Call-ID: b89rjhnedlrfjflslj40a222

CSeq: 47 NOTIFY

Subscription-State: active ;expires=1800

Event: call-completion

Contact: <sip:tas.home2.net>

Content-Type: application/call-completion

Content-Length: (…)

cc-state: ready

cc-service retention

25 to 28: The originating AS initiates the CCBS recall to UE A (by sending a REFER request, the "m" SIP URI parameter set to "BS" will be included in the Request-URI of the REFER request. UE-A confirms the REFER request.

Table A.1-7: REFER request (Originating AS to S-CSCF)

REFER sip:user1_public1@home1.net;m=BS SIP/2.0

Via: SIP/2.0/UDP oas.home1.net;branch=z9hG4bK23273846

Max-Forwards: 70

Route: <sip:scscf1.home1.net;lr>

P-Asserted-Identity: <sip:oas.home1.net>

From: <sip:oas.home1.net>; tag=161828

To: <sip:user1_public1@home1.net>

Call-ID: cb03a0s09a2sdfglkj490333

CSeq: 127 REFER

Refer-To: <sip:user2_public2@home2.net;method=INVITE>

Referred-By: <sip:oas.home1.net>

Contact: <sip:oas.home1.net>

Content-Length: 0

29 to 30: UE-A starts the CCBS call by sending an INVITE request to UE-B.

31 to 33: In order to mark the INVITE request as a prioritized request for call-completion, the originating AS adds the "m" SIP URI parameter with the value ‘BS’ to the Request-URI.

Table A.1-8: SIP INVITE request (Originating AS to S-CSCF)

INVITE sip:user2_public2@home2.net;m=BS SIP/2.0

Via: SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp;branch=z9hG4bKnashds7

Max-Forwards: 70

Route: sip:pcscf1.home1.net:7531;lr;comp=sigcomp>, <sip:orig@scscf1.home1.net;lr>

Accept-Contact: *;+g.3gpp.icsi-ref="urn%3Aurn-7%3gpp-service.ims.icsi.mmtel"

Privacy: none

From: <sip:user1_public1@home1.net>; tag=171829

To: <sip:user2_public2@home2.net>

Call-ID: cb03a0s09a2sdfglkj490444

Call-Info:<sip:user1_public1@home1.net>;purpose=call-completion;m=BS

CSeq: 154 INVITE

Supported: 100rel; precondition, gruu, 199

Require: sec-agree

Contact: <sip:user1_public1@home1.net;gr=urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bg6>;+g.3gpp.icsi-ref="urn%3Aurn-7%3gpp-service.ims.icsi.mmtel"

Allow: INVITE, ACK, CANCEL, BYE, PRACK, UPDATE

Accept: application/sdp,application/3gpp-ims+xml

Content-Type: application/sdp

Content-Length: (…)