I currently have a working RFC 4575 implementation based on the JAIN-SIP stack. (both client and server) I haven't tried integrating this into the SIP Communicator code base, but it makes sense to use something standard like this as a code base, and I'm willing to contribute the work I've done to the SIP Communicator project in this capacity. Currently we're using this for a 7-way conference environment utilizing JAIN-SIP and JMF.
Who would I talk to about working this into the SIP Communicator code base as the basis for a multi-way conference? I'm sure I'm forgetting some RFCs that I've worked into this, but I'm also sure my code needs a lot more unit tests to ensure RFC compliance before it can be called "done".