2.5.20 Share a Whiteboard


This use case, illustrated in the following diagram, describes how a protocol client can share a whiteboard in a conference. This section follows the behavior as described in product behavior note.<31>

Steps for sharing a whiteboard

Figure 19: Steps for sharing a whiteboard



  • The protocol client is present in a Communications Server conference, similar to what is described in section 2.5.17, and is subscribed to conference events, as described in section 2.5.18.


  1. The protocol client sends a SIP INFO addUser request to the protocol server to start a data-conferencing session with Communications Server, as described in [MS-CONFBAS].

  2. Communications Server accepts the incoming message with a SIP 202 acknowledgement.

  3. Communications Server sends a SIP INFO addUser response to the protocol client with response details, as described in [MS-CONFBAS]. These details allow the protocol client to connect and authenticate to the PSOM Shared Object Messaging (PSOM) media session.

  4. The protocol client sends a SIP 200 OK message to Communications Server to acknowledge successful dialog communication.

  5. The protocol client connects and authenticates to Communications Server with a PSOM data session, as described in [MS-PSOM]. The protocol client then adds a whiteboard.


  • PSOM data is flowing between the protocol client and Communications Server.