A.3 CAT forking model signalling flows

24.1823GPPIP Multimedia Subsystem (IMS) Customized Alerting Tones (CAT)Protocol specificationRelease 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

A.3.1 Introduction

The following flows show establishment of a session between UE#1 and UE#2, using the forking model described in clause 4.5.5.3.2 to provide CAT to UE#1. The following flows are included:

– clause A.3.2 shows CAT, using the forking, model, when UE#1 and UE#2 have resources available;

– clause A.3.3 shows CAT, using the forking, model, when UE#1 does not have resources available;

– clause A.3.4 shows CAT, using the forking, model, when UE#2 does not have resources available;

A.3.2 CAT when UE#1 and UE#2 have resources available

Figure A.3.2-1: CAT, no resource reservation

1 INVITE request (UE#1 to S-CSCF) see example in table A.3.2-1

UE#1 sends a SIP INVITE request to the intermediate IM CN subsystem.

Table A.3.2-1: INVITE request (UE#1 to CAT-AS)

INVITE tel:+1-212-555-2222 SIP/2.0

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

Max-Forwards: 70

Route: <sip:pcscf1.visited1.net:7531;lr;comp=sigcomp>, <sip:scscf1.home1.net;lr>

P-Preferred-Identity: "John Doe" <sip:user1_public1@home1.net>

P-Access-Network-Info: IEEE-802.11a

P-Preferred-Service: urn:urn-7:3gpp-service.ims.icsi.mmtel

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

Privacy: none

P-Early-Media: supported

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

To: <tel:+1-212-555-2222>

Call-ID: cb03a0s09a2sdfglkj490333

Cseq: 127 INVITE

Require: sec-agree

Recv-Info: infoDtmf

Supported: precondition, 100rel, gruu, 199

Proxy-Require: sec-agree

Security-Verify: ipsec-3gpp; q=0.1; alg=hmac-sha-1-96; spi-c=98765432; spi-s=87654321; port-c=8642; port-s=7531

Contact:<sip: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"

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

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

Content-Type: application/sdp

Content-Length: (…)

v=0

o=- 2987933615 2987933615 IN IP6 6666::aaa:bbb:ccc:ddd

s=-

c=IN IP6 6666::aaa:bbb:ccc:ddd

t=0 0

m=video 3400 RTP/AVP 98

b=AS:75

a=curr:qos local sendrecv

a=curr:qos remote none

a=des:qos mandatory local sendrecv

a=des:qos none remote sendrecv

a=rtpmap:98 H263

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

m=audio 3456 RTP/AVP 97 96

b=AS:25.4

a=curr:qos local sendrecv

a=curr:qos remote none

a=des:qos mandatory local sendrecv

a=des:qos none remote sendrecv

a=rtpmap:97 AMR

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

a=rtpmap:96 telephone-event

Supported: The UE indicates support for preconditions, reliable provisional responses, gruu and the 199 provisional response

Recv-Info: The UE indicates willingness to receive DTMF Info Packages in INFO requests.

P-Early-Media: The UE indicates support for the P-Early-Media header.

SDP: The SDP offer (SDP_O) contains a set of codecs supported by UE#1 and desired by the calling user for this session. The local preconditions are indicated as fulfilled.

2 INVITE request (S-CSCF to CAT-AS)

The S-CSCF forwards the SIP INVITE request to the CAT-AS.

The CAT-AS instructs the MRF to reserve CAT resources.

3-4 INVITE request (CAT-AS to UE#2)

The CAT-AS forwards the request to UE#2.

5-6 180 (Ringing) provisional response (UE#2 to CAT-AS)

The called party is alerted. UE#2 sends a SIP 180 (Ringing) provisional response for the INVITE request to the CAT-AS.

The CAT-AS terminates the provisional response.

7-8 183 (Session Progress) provisional response (CAT-AS to UE#1) see example in table A.3.2-2

The CAT-AS sends a reliable SIP 183 (Session Progress) provisional response to UE#1.

An early dialog (D1) is established between UE#1 and the CAT-AS.

NOTE: As an alternative, the CAT-AS can send the SIP 183 (Session Progress) provisional response when the initial SIP INVITE request is received from UE#1.

Table A.3.2-2: 183 (Session Progress) response (CAT-AS to UE#1)

SIP/2.0 183 Session Progress

Via: SIP/2.0/UDP scscf2.home2.net;branch=z9hG4bK764z87.1, SIP/2.0/UDP icscf2_s.home2.net;branch=z9hG4bK871y12.1, SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bK332b23.1pcscf1.visited1.net;branch=z9hG4bK240f34.1, SIP/2.0/UDP pcscf1.visited1.net;branch=z9hG4bK240f34.1, SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp;branch=z9hG4bKnashds7

Record-Route: <sip:pcscf2.visited2.net:5088;lr;comp=sigcomp>

From:

To: <tel:+1-212-555-2222>;tag=2236

Call-ID:

Cseq:

Require: 100rel

Recv-Info: infoDtmf

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

RSeq: 9022

P-Early-Media: sendrecv

Contact: <sip:cat-as.home1.net>;+g.3gpp.icsi_ref="urn%3Aurn-7%3gpp-service.ims.icsi.mmtel"

Content-Type: application/sdp

Content-Length: (…)

v=0

o=- 2987933615 2987933615 IN IP6 6666::eee:fff:bbb:aaa

s=-

c=IN IP6 6666::eee:fff:bbb:aaa

t=0 0

m=video 3400 RTP/AVP 98

b=AS:75

a=curr:qos local sendrecv

a=curr:qos remote sendrecv

a=des:qos mandatory local sendrecv

a=des:qos mandatory remote sendrecv

a=rtpmap:98 H263

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

a=content:g.3gpp.cat

m=audio 3456 RTP/AVP 97 96

b=AS:25.4

a=curr:qos local sendrecv

a=curr:qos remote sendrecv

a=des:qos mandatory local sendrecv

a=des:qos mandatory remote sendrecv

a=rtpmap:97 AMR

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

a=content:g.3gpp.cat

P-Early-Media: The CAT-AS requests authorization for early media.

Recv-Info: The CAT-AS indicates willingness to receive DTMF Info Packages in INFO requests.

SDP: The SDP answer (SDP_A) contains a set of codecs supported to be used for CAT and, in this example, includes a SDP "a=content" attribute with a "g.3gpp.cat" value for each media description. The SDP content is based on information received from the MRF. The local preconditions are indicated as fulfilled.

9-10 PRACK request (UE#1 to CAT-AS)

UE#1 sends a SIP PRACK request, which acknowledges the SIP 183 (Session Progress) provisional response, to the CAT-AS.

The CAT-AS instructs the MRF to play CAT media.

11-12 200 (OK) response to PRACK request (CAT-AS to UE#1)

The CAT-AS sends a SIP 200 (OK) response for the SIP PRACK request to UE#1.

13-14 200 (OK) response to INVITE request (UE#2 to CAT-AS) see example in table A.3.2-3

The called party answers the call. UE#2 sends a SIP 200 (OK) final response for the SIP INVITE request to the CAT-AS.

The CAT-AS instructs the MRF to stop CAT media.

Table A.3.2-3: 200 (OK) response (UE#2 to CAT-AS)

SIP/2.0 200 OK

Via: SIP/2.0/UDP pcscf2.visited2.net:5088;comp=sigcomp;branch=z9hG4bK361k21.1, SIP/2.0/UDP scscf2.home2.net;branch=z9hG4bK764XC12.1, SIP/2.0/UDP catas.home2.net;branch=z9hG4bK764Q32.1, SIP/2.0/UDP scscf2.home2.net;branch=z9hG4bK764z87.1, SIP/2.0/UDP icscf2_s.home2.net;branch=z9hG4bK871y12.1, SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bK332b23.1, SIP/2.0/UDP pcscf1.visited1.net;branch=z9hG4bK240f34.1, SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp;branch=z9hG4bKnashds7

Record-Route: <sip:pcscf2.visited2.net:5088;lr;comp=sigcomp>, <sip:scscf2.home2.net;lr>, <sip:scscf1.home1.net;lr>, <sip:pcscf1.visited1.net;lr>

From:

To: <tel:+1-212-555-2222>;tag=6322

Call-ID:

Cseq:

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

Contact: <sip:user2_public1@home2.net;gr=urn:uuid:2ad8950e-48a5-4a74-8d99-ad76cc7fc74>;+g.3gpp.icsi_ref="urn%3Aurn-7%3gpp-service.ims.icsi.mmtel"

Content-Type: application/sdp

Content-Length: (…)

v=0

o=- 2987933615 2987933615 IN IP6 6666::eee:fff:aaa:bbb

s=-

c=IN IP6 6666::eee:fff:aaa:bbb

t=0 0

m=video 3400 RTP/AVP 98

b=AS:75

a=curr:qos local sendrecv

a=curr:qos remote sendrecv

a=des:qos mandatory local sendrecv

a=des:qos mandatory remote sendrecv

a=rtpmap:98 H263

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

m=audio 3456 RTP/AVP 97 96

b=AS:25.4

a=curr:qos local sendrecv

a=curr:qos remote sendrecv

a=des:qos mandatory local sendrecv

a=des:qos mandatory remote sendrecv

a=rtpmap:97 AMR

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

SDP: The SDP answer (SDP_A) contains a set of codecs to be used for the session. If preconditions are used, they are indicated as fulfilled.

15-16 200 (OK) response to INVITE request (CAT-AS to UE#1)

The CAT-AS forwards the SIP 200 (OK) response to UE#1.

A dialog (D2) is established between UE#1 and UE#2.

The early dialog (D1) between UE#1 and the CAT-AS is terminated.

17-78 ACK request (UE#1 to UE#2)

UE#1 sends a SIP ACK request, which acknowledges the SIP 200 (OK) final response, to UE#2.

A.3.3 CAT when UE#1 does not have required resources available while UE#2 has resources available

Figure A.3.3-1: CAT, UE#1 does not have required resources available

1 INVITE request (UE#1 to CAT-AS) see example in table A.3.3-1

UE#1 sends a SIP INVITE request to the intermediate IM CN subsystem.

Table A.3.3-1: INVITE request (UE#1 to CAT-AS)

INVITE tel:+1-212-555-2222 SIP/2.0

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

Max-Forwards: 70

Route: <sip:pcscf1.visited1.net:7531;lr;comp=sigcomp>, <sip:scscf1.home1.net;lr>

P-Preferred-Identity: "John Doe" <sip:user1_public1@home1.net>

P-Access-Network-Info: 3GPP-UTRAN-TDD; utran-cell-id-3gpp=234151D0FCE11

P-Preferred-Service: urn:urn-7:3gpp-service.ims.icsi.mmtel

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

Privacy: none

P-Early-Media: supported

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

To: <tel:+1-212-555-2222>

Call-ID: cb03a0s09a2sdfglkj490333

Cseq: 127 INVITE

Require: sec-agree

Recv-Info: infoDtmf

Supported: precondition, 100rel, gruu, 199

Proxy-Require: sec-agree

Security-Verify: ipsec-3gpp; q=0.1; alg=hmac-sha-1-96; spi-c=98765432; spi-s=87654321; port-c=8642; port-s=7531

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"

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

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

Content-Type: application/sdp

Content-Length: (…)

v=0

o=- 2987933615 2987933615 IN IP6 6666::aaa:bbb:ccc:ddd

s=-

c=IN IP6 6666::aaa:bbb:ccc:ddd

t=0 0

m=video 3400 RTP/AVP 98

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=rtpmap:98 H263

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=rtpmap:97 AMR

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

a=rtpmap:96 telephone-event

Supported: The UE indicates support for preconditions, reliable provisional responses, gruu and the 199 provisional response.

Recv-Info: The UE indicates willingness to receive DTMF Info Packages in INFO requests.

P-Early-Media: The UE indicates support for the P-Early-Media header.

SDP: The SDP offer (SDP_O) contains a set of codecs supported by UE#1 and desired by the user at UE#1 for this session. The local preconditions are indicated as not fulfilled.

2 INVITE request (S-CSCF to CAT-AS)

The S-CSCF forwards the SIP INVITE request to the CAT-AS.

The CAT-AS instructs the MRF to reserve CAT resources.

3-4 INVITE request (CAT-AS to UE#2)

The CAT-AS forwards the SIP INVITE request to UE#2.

5-6 183 (Session Progress) provisional response (CAT-AS to UE#1) see example in table A.3.3-2

The CAT-AS sends a reliable SIP 183 (Session Progress) provisional response to UE#2.

An early dialog (D1) is established between UE#1 and the CAT-AS.

NOTE: As an alternative, the CAT-AS can send the SIP 183 (Session Progress) provisional response when a SIP 180 (Ringing) provisional response is received from UE#2.

Table A.3.3-2: 183 (Session Progress) response (CAT-AS to UE#1)

SIP/2.0 183 Session Progress

Record-Route: <sip:pcscf2.visited2.net:5088;lr;comp=sigcomp>

From:

To: <tel:+1-212-555-2222>;tag=2236

Call-ID:

Cseq:

Require: 100rel

Recv-Info: infoDtmf

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

RSeq: 9022

P-Early-Media: sendrecv

Contact: <sip:cat-as.home1.net;+g.3gpp.icsi_ref="urn%3Aurn-7%3gpp-service.ims.icsi.mmtel">

Content-Type: application/sdp

Content-Length: (…)

v=0

o=- 2987933615 2987933615 IN IP6 6666::eee:fff:bbb:aaa

s=-

c=IN IP6 6666::eee:fff:bbb:aaa

t=0 0

m=video 3400 RTP/AVP 98

b=AS:75

a=curr:qos local sendrecv

a=curr:qos remote none

a=des:qos mandatory local sendrecv

a=des:qos mandatory remote sendrecv

a=rtpmap:98 H263

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

a=content:g.3gpp.cat

m=audio 3456 RTP/AVP 97 96

b=AS:25.4

a=curr:qos local sendrecv

a=curr:qos remote none

a=des:qos mandatory local sendrecv

a=des:qos mandatory remote sendrecv

a=rtpmap:97 AMR

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

a=content:g.3gpp.cat

P-Early-Media: The CAT-AS requests authorization for early media.

Recv-Info: The CAT-AS indicates willingness to receive DTMF Info Packages in INFO requests.

7-8 PRACK request (UE#1 to CAT-AS) see example in table A.1.3-4

UE#1 sends a SIP PRACK request, which acknowledges the SIP 183 (Session Progress) provisional response, to the CAT-AS.

Table A.3.3-3: PRACK request (UE#1 to CAT-AS)

PRACK sip:cat-as.home1.net

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

Max-Forwards: 70

Route: <sip:pcscf1.visited1.net:7531;lr;comp=sigcomp>, <sip:orig@scscf1.home1.net;lr>

From:

To: <tel:+12125552222> tag=2236

Call-ID:

Cseq: 129 PRACK

Rack: 9022

Require: sec-agree

Proxy-Require: sec-agree

Security-Verify: ipsec-3gpp; q=0.1; alg=hmac-sha-1-96; ealg=aes-cbc; spi-c=98765432; spi-s=87654321; port-c=8642; port-s=7531

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"

Content-Type: application/sdp

Content-Length: (…)

v=0

o=- 2987933615 2987933669 IN IP6 6666::aaa:bbb:ccc:ddd

s=-

c=IN IP6 6666::aaa:bbb:ccc:ddd

t=0 0

m=video 3400 RTP/AVP 98

b=AS:75

a=curr:qos local sendrecv

a=curr:qos remote sendrecv

a=des:qos mandatory local sendrecv

a=des:qos mandatory remote sendrecv

a=rtpmap:98 H263

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

m=audio 3456 RTP/AVP 97 96

b=AS:25.4

a=curr:qos local sendrecv

a=curr:qos remote sendrecv

a=des:qos mandatory local sendrecv

a=des:qos mandatory remote sendrecv

a=rtpmap:97 AMR

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

SDP: The local preconditions are indicated as fulfilled, and media are set to "sendrecv".

9-10 200 (OK) response to PRACK request (CAT-AS to UE#1)

The CAT-AS sends a SIP 200 (OK) response for the SIP PRACK request to UE#1.

11-12 180 (Ringing) provisional response (UE#2 to CAT-AS) see example in table A.3.3-4

The called party is alerted. UE#2 sends an unreliable SIP 180 (Ringing) provisional response for the INVITE request to the CAT-AS.

The CAT-AS instructs the MRF to start CAT media.

Table A.3.3-4: 180 (Ringing) response (UE#2 to CAT-AS)

SIP/2.0 180 Ringing

Record-Route: <sip:pcscf2.visited2.net:5088;lr;comp=sigcomp>, <sip:scscf2.home2.net;lr>, <sip:scscf1.home1.net;lr>, <sip:pcscf1.visited1.net;lr>

From:

To: <tel:+1-212-555-2222>;tag=6322

Call-ID:

Cseq:

Require: 100rel, precondition

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

RSeq: 9021

Contact: <sip:user2_public1@home2.net;gr=urn:uuid:2ad8950e-48a5-4a74-8d99-ad76cc7fc74>;+g.3gpp.icsi_ref="urn%3Aurn-7%3gpp-service.ims.icsi.mmtel"

Content-Type: application/sdp

Content-Length: (…)

v=0

o=- 2987933615 2987933615 IN IP6 6666::eee:fff:aaa:bbb

s=-

c=IN IP6 6666::eee:fff:aaa:bbb

t=0 0

m=video 3400 RTP/AVP 98

b=AS:75

a=curr:qos local sendrecv

a=curr:qos remote none

a=des:qos mandatory local sendrecv

a=des:qos mandatory remote sendrecv

a=rtpmap:98 H263

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

m=audio 3456 RTP/AVP 97 96

b=AS:25.4

a=curr:qos local sendrecv

a=curr:qos remote none

a=des:qos mandatory local sendrecv

a=des:qos mandatory remote none

a=rtpmap:97 AMR

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

SDP: The SDP answer (SDP_A) contains a set of codecs to be used for the session. The local preconditions are indicated as fulfilled.

13-14 183 (Session Progress) provisional response (CAT-AS to UE#1)

The CAT-AS changes the response code to SIP 183 (Session Progress) response and forwards the SIP provisional response to UE#1.

An early dialog (D2) is established between UE#1 and UE#2.

15-16 PRACK request (UE#1 to UE#2)

UE#1 sends a SIP PRACK request, which acknowledges the SIP 183 (Session Progress) provisional response, to UE#2.

SDP: The local preconditions are indicated as fulfilled, and media are set to "sendrecv".

17-18 200 (OK) response to PRACK request (UE#2 to UE#1)

UE#2 sends a SIP 200 (OK) response for the SIP PRACK request to UE#1.

19-20 200 (OK) response to INVITE request (UE#2 to CAT-AS)

The called party answers the call. UE#2 sends a SIP 200 (OK) final response for the SIP INVITE request to the CAT-AS.

21-22 200 (OK) response to INVITE request (CAT-AS to UE#1)

The CAT-AS forwards the SIP 200 (OK) response to UE#1.

The CAT-AS instructs the MRF to stop CAT media.

The early dialog (D1) between UE#1 and the CAT-AS is terminated.

23-24 ACK request (UE#1 to UE#2)

UE#1 sends a SIP ACK request, which acknowledges the SIP 200 (OK) final response, to UE#2.

A.3.4 CAT when UE#1 has resources available while UE#2 does not have required resources available

Figure A.3.4-1: CAT, UE#2 does not have required resources available

1 INVITE request (UE#1 to CAT-AS) see example in table A.3.4-1

UE#1 sends a SIP INVITE request to the intermediate IM CN subsystem.

Table A.3.4-1: INVITE request (UE#1 to CAT-AS)

INVITE tel:+1-212-555-2222 SIP/2.0

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

Max-Forwards: 70

Route: <sip:pcscf1.visited1.net:7531;lr;comp=sigcomp>, <sip:scscf1.home1.net;lr>

P-Preferred-Identity: "John Doe" <sip:user1_public1@home1.net>

P-Access-Network-Info: IEEE-802.11a

P-Preferred-Service: urn:urn-7:3gpp-service.ims.icsi.mmtel

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

Privacy: none

P-Early-Media: supported

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

To: <tel:+1-212-555-2222>

Call-ID: cb03a0s09a2sdfglkj490333

Cseq: 127 INVITE

Require: sec-agree

Recv-Info: infoDtmf

Supported: precondition, 100rel, gruu, 199

Proxy-Require: sec-agree

Security-Verify: ipsec-3gpp; q=0.1; alg=hmac-sha-1-96; spi-c=98765432; spi-s=87654321; port-c=8642; port-s=7531

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"

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

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

Content-Type: application/sdp

Content-Length: (…)

v=0

o=- 2987933615 2987933615 IN IP6 6666::aaa:bbb:ccc:ddd

s=-

c=IN IP6 6666::aaa:bbb:ccc:ddd

t=0 0

m=video 3400 RTP/AVP 98

b=AS:75

a=curr:qos local sendrecv

a=curr:qos remote none

a=des:qos mandatory local sendrecv

a=des:qos none remote sendrecv

a=rtpmap:98 H263

m=audio 3456 RTP/AVP 97 96

b=AS:25.4

a=curr:qos local sendrecv

a=curr:qos remote none

a=des:qos mandatory local sendrecv

a=des:qos none remote sendrecv

a=rtpmap:97 AMR

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

a=rtpmap:96 telephone-event

Supported: The UE indicates support for preconditions, reliable provisional responses, gruu and the 199 provisional response.

Recv-Info: The UE indicates willingness to receive DTMF Info Packages in INFO requests.

P-Early-Media: The UE indicates support for the P-Early-Media header.

SDP: The SDP offer (SDP_O) contains a set of codecs supported by UE#1 and desired by the user at UE#1 for this session. The SDP contains an indication that the local preconditions are fulfilled.

2 INVITE request (S-CSCF to CAT-AS)

The S-CSCF forwards the SIP INVITE request to the CAT-AS.

The CAT-AS instructs the MRF to reserve CAT resources.

3-4 INVITE request (CAT-AS to UE#2)

The CAT-AS forwards the SIP INVITE request to UE#2.

5-6 180 (Ringing) provisional response (UE#2 to CAT-AS) see example in table A.3.4-2

The called party is alerted. UE#2 sends a SIP 180 (Ringing) provisional response for the INVITE request to the CAT-AS.

Table A.3.4-2: 180 (Ringing) response (UE#2 to CAT-AS)

SIP/2.0 180 Ringing

Record-Route: <sip:pcscf2.visited2.net:5088;lr;comp=sigcomp>, <sip:scscf2.home2.net;lr>, <sip:scscf1.home1.net;lr>, <sip:pcscf1.visited1.net;lr>

From:

To: <tel:+1-212-555-2222>;tag=6322

Call-ID:

Cseq:

Require: 100rel, precondition

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

RSeq: 9021

Contact: <sip:user2_public1@home2.net;gr=urn:uuid:2ad8950e-48a5-4a74-8d99-ad76cc7fc74>;+g.3gpp.icsi_ref="urn%3Aurn-7%3gpp-service.ims.icsi.mmtel"

Content-Type: application/sdp

Content-Length: (…)

v=0

o=- 2987933615 2987933615 IN IP6 6666::eee:fff:aaa:bbb

s=-

c=IN IP6 6666::eee:fff:aaa:bbb

t=0 0

m=video 3400 RTP/AVP 98

b=AS:75

a=curr:qos local sendrecv

a=curr:qos remote sendrecv

a=des:qos mandatory local sendrecv

a=des:qos mandatory remote sendrecv

a=rtpmap:98 H263

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

a=content:g.3gpp.cat

m=audio 3456 RTP/AVP 97 96

b=AS:25.4

a=curr:qos local sendrecv

a=curr:qos remote sendrecv

a=des:qos mandatory local sendrecv

a=des:qos mandatory remote none

a=rtpmap:97 AMR

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

a=content:g.3gpp.cat

SDP: The SDP answer (SDP_A) contains a set of codecs to be used for the session and, in this example, includes a SDP "a=content" attribute with a "g.3gpp.cat" value for each media description. The local preconditions are indicated as fulfilled.

7-8 183 (Session Progress) provisional response (CAT-AS to UE#1)

The CAT-AS changes the response code to 183 (Session Progress) response, and forwards the SIP provisional response to UE#1.

An early dialog (D2) is established between UE#1 and UE#2.

9-10 PRACK request (UE#1 to UE#2)

UE#1 sends a SIP PRACK request, which acknowledges the 183 (Session Progress) provisional response, to UE#2.

11-12 200 (OK) response to PRACK (UE#2 to UE#1)

UE#2 sends a SIP 200 (OK) response for the SIP PRACK request to UE#1.

13-14 183 (Session Progress) provisional response (CAT-AS to UE#1) see example in table A.3.3-3

The CAT-AS sends a reliable SIP 183 (Session Progress) provisional response to UE#2.

An early dialog (D1) is established between UE#1 and the CAT-AS.

NOTE: As an alternative, the CAT-AS can send the SIP 183 (Session Progress) provisional response when the initial SIP INVITE request is received from UE#1.

Table A.3.3-4: 183 (Session Progress) response (CAT-AS to UE#1)

SIP/2.0 183 Session Progress

Record-Route: <sip:pcscf2.visited2.net:5088;lr;comp=sigcomp>

From:

To: <tel:+1-212-555-2222>;tag=2236

Call-ID:

Cseq:

Require: 100rel

Recv-Info: infoDtmf

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

RSeq: 9022

P-Early-Media: sendrecv

Contact: <sip:cat-as.home1.net>;+g.3gpp.icsi_ref="urn%3Aurn-7%3gpp-service.ims.icsi.mmtel"

Content-Type: application/sdp

Content-Length: (…)

v=0

o=- 2987933615 2987933615 IN IP6 6666::eee:fff:bbb:aaa

s=-

c=IN IP6 6666::eee:fff:bbb:aaa

t=0 0

m=video 3400 RTP/AVP 98

b=AS:75

a=curr:qos local sendrecv

a=curr:qos remote sendrecv

a=des:qos mandatory local sendrecv

a=des:qos mandatory remote sendrecv

a=rtpmap:98 H263

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

m=audio 3456 RTP/AVP 97 96

b=AS:25.4

a=curr:qos local sendrecv

a=curr:qos remote sendrecv

a=des:qos mandatory local sendrecv

a=des:qos mandatory remote sendrecv

a=rtpmap:97 AMR

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

P-Early-Media: The CAT-AS requests authorization for early media.

Recv-Info: The CAT-AS indicates willingness to receive DTMF Info Packages in INFO requests.

SDP: The SDP answer (SDP_A) contains a set of codecs supported to be used for CAT. The SDP content is based on information received from the MRF. The SDP contains an indication that the local preconditions are fulfilled.

15-16 PRACK request (UE#1 to CAT-AS)

UE#1 sends a SIP PRACK request, which acknowledges the SIP 183 (Session Progress) provisional response, to the CAT-AS.

The CAT-AS instructs the MRF to start CAT media.

17-18 200 (OK) response to PRACK request (CAT-AS to UE#1)

The CAT-AS sends a SIP 200 (OK) response for the SIP PRACK request to UE#1.

19-20 200 (OK) response to INVITE request (UE#2 to CAT-AS)

The called party answers the call. UE#2 sends a SIP 200 (OK) final response for the SIP INVITE request to the CAT-AS.

The CAT-AS instructs the MRF to stop CAT media.

21-22 200 (OK) response to INVITE request (CAT-AS to UE#1)

The CAT-AS forwards the SIP 200 (OK) response to UE#1.

The early dialog (D1) between UE#1 and the CAT-AS is terminated.

23-24 ACK request (UE#1 to UE#2)

UE#1 sends a SIP ACK request, which acknowledges the 200 (OK) final response, to UE#2.