Integrating Telephony with OCS R2
Updated for OCS 2007 R2, this white paper covers everything you want to know about Voice Interoperability with OCS. Topics include Media Gateways, IP-PBXs, SIP Trunking, PBX integration Scenarios, Standards Compliance, Integration Features and Migration Strategies.
Download it from https://www.microsoft.com/downloads/details.aspx?familyid=8CDE0C3A-042E-445B-A514-2D12ED5B2AC2&displaylang=en