24.5053GPPProtocol specificationPSTN/ISDN simulation services: Conference (CONF)Release 8TISPANTS
A.2.1 Invite other user to 3PTY CONF by sending REFER request
Figure A.2 depictures a flow where two UEs, UE-1 and UE-2, are engaged in a call. At some point in time, UE-1 decides to involve UE-3 into the communication and activate the 3PTY CONF service. UE-1 puts UE-2 on hold, initiates a session toward UE-3 to get the user’s permission to start 3PTY call, creates the conference, and moves the original communication with both UE-2 and UE-3 to the conference server.
Figure A.2: Call flow for 3PTY conference
A.2.2 Invite other user to 3PTY CONF by sending INVITE request with URI list
Figure A.3 depictures a flow where UA-A is involved in 2 communications with UA-B and UA-C, both 2 communications are on-hold. The AS is involved in both 2 communications as a B2BUA.
When user A intends to start the 3PTY conference, UA-A sends INVITE to the AS to create the conference and indicates that certain dialogs shall be re-used for this conference, The AS sends re-INVITEs in the indicated dialogs and connects the media to the conference bridge. The dialogs can be indicated by adding the Call-ID header field, the From header field and the To header field to the entries in the URI list of the initial INVITE
Figure A.3: Call flow for 3PTY conference
1: UA-A creates a conference and invites user B and user C to the conference by sending an INVITE to the Conference Factory URI and including URI list in the INVITE request, UA-A indicates the certain dialogs which be re-used for this conference in the uri list by ? mechanism.
INVITE CONF AS
To: CONF AS
<?xml version="1.0" encoding="UTF-8"?>
<entry uri="B?Call-ID=1a&From=A%3Btag%3Da&To=B%3Btag%3Db" cp:copyControl="to"/>
<entry uri="C?Call-ID=2a&From=A%3Btag%3Da&To=C%3Btag%3Dc" cp:copyControl="to"/>
2: AS verifies if the dialogs in URI list matches to a partial dialog which AS already involved, In the case of a match the AS use this dialog ID information to send re-INVITE request to UA-B and UA-C in the partial dialogs between the AS and the invited users in order to connect the media of the invited users to the MRFP.
Annex B (informative):
Publication as ETSI TS 183 005
Conversion to 3GPP TS 24.505
Based on the decision in CT#39 version 8.0.0 created by MCC
Emergency call CONF suppression