The Following figure shows the message flow between conferencing components when a client joins a conference by issuing an addUserC3P dial-in command.

Client joining media with a Web Conferencing Server using addUser dial-in

The following is a description of the message flow between conferencing components when a client joins a conference by sending an addUserC3P command to the Web Conferencing Server:

Step 1.The client sends an INFO request with an addUserdial-in command to the Focus. The client uses the focus/conference URI it received in the notification document.

Step 2.The Focus determines if a conferencing server has been assigned to support this particular media type for this conference. If a conferencing server has not been assigned, the Focus sends an HTTP request to the Conferencing Server Factory asking it to allocate a conferencing server for this conference. In the diagram, it is assumed that the conferencing server has been assigned to the conference. The Focus then sends an HTTP request to the designated conferencing server asking it to expect a new participant ( addUser). Any bootstrapping requests that the Focus sends to initialize the conference on the conferencing server are not included in the call flow diagram.

Step 2.1.The conferencing server sends a successful response for the addUserrequest. The response contains the actual URL it wants the conference participant to use to talk to the conferencing server. If the client is joining a Web Conferencing Server, the URL is a PSOM URL. Authorization information, if any, is also included in the response.

Step 3.The Focus sends the PSOM connection information to the client.

Step 4.The client directly establishes a PSOM channel with the Web Conferencing Server.

Step 5.After the client successfully joins the Web Conferencing Server, it sends a participant joined event to the Focus.

Step 6.The Focus sends a participant joined conferencing server state change notification to all clients subscribed to the conference state.

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BENOTIFY sip:client1@contoso.com SIP/2.0 SIP headers... <conference-state version="1" state="partial" entity="sip:Ted@contoso.com;gruu;opaque=app:conf:focus:id:1234"> <user entity="bob@contoso.com" state="full"> <display-text>Bob Kelly</display-text> <endpoint entity="addf"> <state>connected</state> <!-- MEDIA --> <media entity="2" state="full"> <display-text>data collab</display-text> <proto>dataCollab</proto> </media> </endpoint> </user> <....Other conf Info...> </conference-state>