MS Speech Server 2007 - can come sep. from communication server.
Authentication requires a Server CAL.
MS Communication - AIM, MSN, (license fees apply)
SALT and VoiceXML
Managed code IVRs - using .NET and WF
API Client - Office communicator SDK - send IM's and control client
Unified communications managed api - setup SIP endpoints
Speech Server development componets adds IVR wizards and WF activities for VS2008. SIP over TCP is supported in Speech Server but UDP is not! (very interesting)
Uses some special SIP routing headers that are not supported by everyone.