کد:
http://communicationsserverteam.com/archive/2009/04/28/473.aspx

There is a new capability in R2 CWA to initiate or join an audio conference. Here’s how it works.
Vivian is logged onto CWA as a remote user. Amy and Hao are on her buddy list – they’re both logged onto Communicator either inside or outside the corporation:



Vivian begins with an IM to Amy:



In the resulting IM dialog Vivian has an audio conference option above her presence icon which she now uses to initiate a call. Vivian is using this IM session to add audio, but alternately she could do this via an existing CWA RDP application sharing session:



To join the conference Vivian can choose her published work number or she can type in another phone number. If Vivian enters another phone number, OCS will normalize it according to her location profile and if it maps to a PBX or PSTN user it will dial out to her via the mediation server. If Vivian is also logged on to Tanjay or OC via MPOP she can take the call that way but she must enter a number to initiate the call.
CWA uses the dial out capabilities of the AVMCU to setup this call so it is a little different from a peer-to-peer call. Vivian selects her work number and the AVMCU calls her work phone (‘Conferencing service is calling you …’):



Vivian’s phone rings and OCS sets up a media stream from the AVMCU to Vivian’s work number. If this was a PSTN or PBX number the media would flow through the mediation server. Signaling or control messages for the conference are sent to CWA from Vivian’s front end server where the conference is hosted. CWA converts the SIP signaling into HTTP which is delivered to the browser. Logging on the front end shows shows the conference being setup through the Centralized Conferencing Control Protocol or C3P (‘CONTENT-TYPE: application/cccp+xml’). Specifically we see C3P commands to add a conference and then add Vivian as a user on the AVMCU. The Focus is the conferencing element on the front end server that handles conferencing setup and maintenance – below we see the C3P AddUser command issued to the Focus:



The highlighted items in the trace show in order from the top the conference ID the focus will reference for the duration of this conference – note this will be the same ID for any associated IM (IMMCU) or application sharing (RDPMCU) in this conference. The user-agent tag shows CWA is initiating this dialog, the application/cccp+xml indicates the payload of this SIP INVITE is C3P commands over XML and finally we see the <addUser> command in the XML body.
Next we see the Focus initiating a call to Vivian at +14255032002:



Vivian now has the first leg of her conference call established so next the Focus initiates a dial-out to Amy:



This invite is to Amy’s sip: URI not a tel: URI. If Amy was also logged in via CWA she could choose to divert the incoming audio invite to a phone number. In this case, Amy is signed onto Communicator and takes the call from her PC:



Vivian and Amy are now on the audio conference together and note Vivian as the conference leader has capabilities to eject Amy from the conference or promote her to leader:



On the CWA server you can also see notifications going through from the Front End and out to Vivian for roster updates; this one is adding Amy as a connected attendee on her roster:



Amy and Vivian’s presence now show ‘In a conference’ since we are making this call happen via conferencing rather than peer-to-peer calling.



It’s easy for Vivian to invite someone else into the conference, here she adds Hao simply by picking him from her buddy list via the Invite control:



Now Vivian, Amy and Hao are on a conference call with both audio/video and IM MCUs servicing the conference. If Vivian or Amy wanted to add application sharing they could easily do this via the application sharing control adjacent to the audio conferencing control.
If you want to take a look at how this works in your environment, use OCS Logger to look at the CWA components on your CWA server as well as the MCUInfra, MCUFactory, SIPStack and S4 components on your Front End server



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