A.5 CCNL invocation

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.5.1: CCNL invocation

Figure A.5.1 shows a basic signalling flow for a CCNL invocation.

Call flows

1 to 4: 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, in accordance with the procedures for services for unregistered users as described in 3GPP TS 24.229 [2].

Table A.5-1: 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

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

5 to 6: The terminating AS inserts a Call-Info header field in the 480 (Temporarily Unavailable) 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 "NL" (not logged-in). It further includes a "purpose" header field parameter set to "call-completion". The 480 (Temporarily Unavailable) response is routed back to the originating AS.

Table A.5-2: 480 (Temporarily Unavailable) response (Terminating AS to S-CSCF))

SIP/2.0 480 Temporarily Unavailable

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=NL

7 to 8: The originating AS sends back a 183 (Session Progress) response to UE-A and initiates IVR procedures. User A is informed that CCNL is possible. User A activates CCNL.

9 to 10: 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 CCNL, the originating AS adds the "m" SIP URI parameter with the value "NL" to the Request-URI. The From header field will include the caller URI. The To header field will include the callee URI. The originating AS also adds a Call-Info header field with the URI of UE-A from the P-Asserted-Identity, a "purpose" header field parameter set to "call-completion", and an m-parameter set to "NL".

Table A.5-3: SUBSCRIBE request (Originating AS to S-CSCF)

SUBSCRIBE sip:tas.home2.net;m=NL 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:oas.home1.net>

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

To: <sip:user2_public2@home2.net>

Call-ID: b89rjhnedlrfjflslj40a222

CSeq: 61 SUBSCRIBE

Event: call-completion

Expires: 2700

Contact: <sip:oas.home1.net>

Content-Length: 0

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

11 to 12: The terminating AS accepts the subscription and starts registration state supervision procedures on the callee.

13 to 16: 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 CCNL.

Table A.5-5: 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=10800

Event: call-completion

Contact: <sip:tas.home2.net>

Content-Type: application/call-completion

Content-Length: (…)

cc-state: queued

cc-service retention

17 to 18: The originating AS forwards the 480 (Temporarily Unavailable) response to UE-A.