A.4.4 User requesting IMS to join another user

24.1473GPPConferencing using the IP Multimedia (IM) Core Network (CN) subsystemRelease 17Stage 3TS

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

A.4.4.1 MRFC/AS is located in user’s home network

Figure A.4.4.1-1 shows how UE#1 invites UE#2 to a conference by sending a REFER request to MRFC/AS. UE#1 has created a conference by using the mechanisms described in subclause 5.3.1.3, and UE#1 has learned the conference URI that identifies this conference.

Figure A.4.4.1-1: User inviting another user to a conference by
sending a REFER request to MRFC/AS

The details of the flows are as follows:

1. UE#1 creates a conference

UE#1 creates a conference as described in subclause 5.3.1.3. Once the conference creation is accomplished, UE#1 has learned the conference URI allocated for this conference.

2. REFER request (UE to P-CSCF) – see example in table A.4.4.1-2

A UE has created a conference and learned the conference URI. Now the UE wants to join another UE to that conference.

Table A.4.4.1-2: REFER request (UE to P-CSCF)

REFER sip: conference1@mrfc1.home1.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.visited1.net:7531;lr;comp=sigcomp>, <sip:orig@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

Privacy: none

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

To: <sip: conference1@mrfc1.home1.net>

Call-ID: cb03a0s09a2sdfglkj490333

Cseq: 127 REFER

Require: sec-agree

Refer-To: <sip:user2_public1@home2.net;method=INVITE>

Proxy-Require: sec-agree

Supported: gruu

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 ;comp=sigcomp>

Content-Length: 0

Request-URI: contains the conference URI as learned during the conference establishment.

3. REFER request (P-CSCF to S-CSCF) – see example in table A.4.4.1-3

The REFER request is forwarded to the S-CSCF.

Table A.4.4.1-3: REFER request (P-CSCF to S-CSCF)

REFER sip: conference1@mrfc1.home1.net SIP/2.0

Via: SIP/2.0/UDP pcscf1.visited1.net;branch=z9hG4bK240f34.1, SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp;branch=z9hG4bKnashds7

Max-Forwards: 69

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

Record-Route: <sip:pcscf1.visited1.net;lr>

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

P-Charging-Vector: ####

P-Access-Network-Info:

Privacy:

From:

To:

Call-ID:

Cseq:

Refer-To:

Supported:

Contact:

Content-Length:

4. Evaluation of initial Filter Criteria

The S-CSCF validates the service profile of this subscriber and evaluates the initial filter criteria.

5. REFER request (S-CSCF to MRFC/AS) – see example in table A.4.4.1-5

The S-CSCF forwards the REFER request to the address obtained by a DNS query. The S-CSCF adds itself to the Record-Route header.

Table A.4.4.1-5: REFER request (S-CSCF to MRFC/AS)

REFER sip:user2_public1@home2.net SIP/2.0

Via: 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

Max-Forwards: 68

Record-Route: <sip:scscf1.home1.net;lr>, <sip:pcscf1.visited1.net;lr>

P-Asserted-Identity: "John Doe" <sip:user1_public1@home1.net>, <tel:+358-50-4821437>

P-Charging-Vector: ####

Privacy:

From:

To:

Call-ID:

Cseq:

Refer-To:

Supported:

Contact:

Content-Length:

6. 200 (OK) response to REFER (MRFC/AS to S-CSCF) – see example in table A.4.4.1-6

The MRFC/AS indicates that it has received the REFER request by sending a 200 (OK) response. This means that MRFC/AS has accepted the REFER request and has begun to process the request. This does not mean, however, that the referred-to resource would have been contacted.

Table A.4.4.1-6: 200 (OK) response to REFER (MRFC/AS to S-CSCF)

SIP/2.0 200 OK

Via: 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:scscf1.home1.net;lr>, <sip:pcscf1.visited1.net;lr>

P-Asserted-Identity: <conference1@mrfc1.home1.net>

P-Charging-Vector: ####

Privacy:none

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

To: <sip:conference1@mrfc1.home1.net>;tag=151170

Call-ID: cb03a0s09a2sdfglkj490333

CSeq: 127 REFER

Contact: <sip:conference1@mrfc1.home1.net>;isfocus

Content-Length:0

Contact: contains the conference URI for the conference allocated at the MRFC/AS and the "isfocus" feature parameter.

7. INVITE request user to conference

The MRFC/AS invites the user, who is indicated in the Refer-To header of the received REFER request. It does apply the procedures as shown in subclause A.4.3.1.3.

8. 200 (OK) response to REFER (S-CSCF to P-CSCF) – see example in table A.4.4.1-8

The S-CSCF forwards the response to the P-CSCF.

Table A.4.4.1-8: 200 (OK) response to REFER (S-CSCF to P-CSCF)

SIP/2.0 200 OK

Via: 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:

P-Asserted-Identity:

P-Charging-Vector: ####

Privacy:

From:

To:

Call-ID:

CSeq:

Contact:

Content-Length:

9. 200 (OK) response to REFER (P-CSCF to UE#1) – see example in table A.4.4.1-9

The P-CSCF forwards the response to UE#1.

Table A.4.4.1-9: 200 (OK) response to REFER (P-CSCF to UE#1)

SIP/2.0 200 OK

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

Record-Route:

P-Asserted-Identity:

Privacy:

From:

To:

Call-ID:

CSeq:

Contact:

Content-Length:

10. NOTIFY request (MRFC/AS to S-CSCF) – see example in table A.4.4.1-10

The MRFC/AS sends a NOTIFY request to inform the S-CSCF about the progress of the REFER request processing. The body of the NOTIFY request contains a fragment of the response as received by the notifying UE for the request that was initiated due to the REFER request.

Table A.4.4.1-10: NOTIFY request (from MRFC/AS to S-CSCF)

NOTIFY sip:user1_public1@home1.net;gr=urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6 ;comp=sigcomp SIP/2.0

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

Max-Forwards: 70

Route: <sip:scscf1.home1.net;lr>, <sip:pcscf1.visited1.net;lr>

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

From: <sip:conference1@mrfc1.home1.net>;tag=151170

Call-ID: cb03a0s09a2sdfglkj490333

CSeq: 42 NOTIFY

Subscription-State: active;expires:7200

Event: refer

Contact: <sip:conference1@mrfc1.home1.net>;isfocus

Content-Length: (…)

Content-Type: message/sipfrag

SIP/2.0 100 Trying

11. NOTIFY request (from S-CSCF to P-CSCF) – see example in table A.4.4.1-11

The S-CSCF forwards the message to the P-CSCF.

Table: A.4.4.1-11: NOTIFY request (from S-CSCF to P-CSCF)

NOTIFY sip:[5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp SIP/2.0

Via: SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bK23436s.1, SIP/2.0/UDP mrfc.home1.net;branch= z9hG4bK23273846

Max-Forwards: 69

Route: <sip:pcscf1.visited1.net;lr>

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

To:

From:

Call-ID:

CSeq:

Subscription-State:

Event:

Contact:

Content-Length: (…)

Content-Type:

(…)

12. NOTIFY request (from P-CSCF to UE#1) – see example in table A.4.4.1-12

The P-CSCF forwards the message to UE#1.

Table A.4.4.1-12: NOTIFY request (from P-CSCF to UE#1)

NOTIFY sip:[5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp SIP/2.0

Via: SIP/2.0/UDP pcscf1.visited1.net:7531;comp=sigcomp;branch=z9hG4bK23433.1, SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bK23436s.1, SIP/2.0/UDP mrfc.home1.net;branch=z9hG4bK23273846

Max-Forwards: 68

Record-Route: <sip:pcscf1.visited1.net;lr>, <sip:scscf1.home1.net;lr>

To:

From:

Call-ID:

CSeq:

Subscription-State:

Event:

Contact:

Content-Length: (…)

Content-Type:

(…)

13. 200 (OK) response (UE to P-CSCF) – see example in table A.4.4.1-13

The UE acknowledges the NOTIFY request with a 200 (OK) response to the P-CSCF.

Table A.4.4.1-13: 200 (OK) response (UE to P-CSCF)

SIP/2.0 200 OK

Via: SIP/2.0/UDP pcscf1.visited1.net:7531;comp=sigcomp;branch=z9hG4bK23433.1, SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bK23436s.1, SIP/2.0/UDP mrfc.home1.net;branch=z9hG4bK23273846

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

Record-Route: <sip:pcscf1.visited1.net;lr>, <sip:scscf1.home1.net;lr>

From:

To:

Call-ID:

CSeq:

Content-Length: 0

14. 200 (OK) response (P-CSCF to S-CSCF) – see example in table A.4.4.1-14

The P-CSCF forwards the 200 (OK) response to the S-CSCF.

Table A.4.4.1-14: 200 (OK) response (P-CSCF to S-CSCF)

SIP/2.0 200 OK

Via: SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bK23436s.1, SIP/2.0/UDP mrfc.home1.net;branch=z9hG4bK23273846

Record-Route:

P-Access-Network-Info:

From:

To:

Call-ID:

CSeq:

Content-Length: 0

15. 200 (OK) response (S-CSCF to MRFC/AS) – see example in table A.4.4.1-15

The S-CSCF forwards the 200 (OK) response to MRFC/AS.

Table A.4.4.1-15: 200 (OK) response (S-CSCF to MRFC/AS)

SIP/2.0 200 OK

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

Record-Route:

From:

To:

Call-ID:

CSeq:

Content-Length: 0

16. Referred user joins the conference.

The referred user joins the conference as described in subclause 5.3.1.4.

17. NOTIFY request (from MRFC/AS to S-CSCF) – see example in table A.4.4.1-17

The MRFC/AS sends a NOTIFY request that indicates that the referred party has joined the conference.

Table A.4.4.1-17: NOTIFY request (from MRFC/AS to S-CSCF)

NOTIFY sip:user1_public1@home1.net;gr=urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6 ;comp=sigcomp SIP/2.0

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

Max-Forwards: 70

Route: <sip:scscf1.home1.net;lr>, <sip:pcscf1.visited1.net;lr>

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

From: <sip:conference1@mrfc1.home1.net>;tag=151170

Call-ID: cb03a0s09a2sdfglkj490333

CSeq: 43 NOTIFY

Subscription-State: terminated

Event: refer

Content-Length: (…)

Content-Type: message/sipfrag

SIP/2.0 200 OK

Subscription-State: indicates that the implicit subscription to the refer event has been terminated.

18. NOTIFY request (from S-CSCF to P-CSCF) – see example in table A.4.4.1-18

The S-CSCF forwards the message to the P-CSCF.

Table 6.3.3.1.1-18: NOTIFY request (from S-CSCF to P-CSCF)

NOTIFY sip:[5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp SIP/2.0

Via: SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bK23436s.1, SIP/2.0/UDP mrfc.home1.net;branch= z9hG4bK23273846

Max-Forwards: 69

Route: <sip:pcscf1.visited1.net;lr>

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

To:

From:

Call-ID:

CSeq:

Subscription-State:

Event:

Content-Length: (…)

Content-Type:

(…)

19. NOTIFY request (from P-CSCF to UE#1) – see example in table A.4.4.1-19

The P-CSCF forwards the message to UE#1.

Table A.4.4.1-19: NOTIFY request (from P-CSCF to UE#1)

NOTIFY sip: [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp SIP/2.0

Via: SIP/2.0/UDP pcscf1.visited1.net:7531;comp=sigcomp;branch=z9hG4bK23433.1, SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bK23436s.1, SIP/2.0/UDP mrfc.home1.net;branch=z9hG4bK23273846

Max-Forwards: 68

Record-Route: <sip:pcscf1.visited1.net;lr>, <sip:scscf1.home1.net;lr>

To:

From:

Call-ID:

CSeq:

Subscription-State:

Event:

Content-Length: (…)

Content-Type:

(…)

20. 200 (OK) response (UE to P-CSCF) – see example in table A.4.4.1-20

The UE acknowledges the NOTIFY request with a 200 (OK) response to the P-CSCF.

Table A.4.4.1-20: 200 (OK) response (UE to P-CSCF)

SIP/2.0 200 OK

Via: SIP/2.0/UDP pcscf1.visited1.net:7531;comp=sigcomp;branch=z9hG4bK23433.1, SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bK23436s.1, SIP/2.0/UDP mrfc.home1.net;branch=z9hG4bK23273846

Record-Route: <sip:pcscf1.visited1.net;lr>, <sip:scscf1.home1.net;lr>

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

From:

To:

Call-ID:

CSeq:

Content-Length: 0

21. 200 (OK) response (P-CSCF to S-CSCF) – see example in table A.4.4.1-21

The P-CSCF forwards the 200 (OK) response to the S-CSCF.

Table A.4.4.1-21: 200 (OK) response (P-CSCF to S-CSCF)

SIP/2.0 200 OK

Via: SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bK23436s.1, SIP/2.0/UDP mrfc.home1.net;branch=z9hG4bK23273846

Record-Route: P-Access-Network-Info:

From:

To:

Call-ID:

CSeq:

Content-Length:

22. 200 (OK) response (S-CSCF to MRFC/AS) – see example in table A.4.4.1-22

The S-CSCF forwards the 200 (OK) response to the MRFC/AS.

Table A.4.4.1-22: 200 (OK) response (S-CSCF to MRFC/AS)

SIP/2.0 200 OK

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

Record-Route:

From:

To:

Call-ID:

CSeq:

Content-Length: