http://blogs.technet.com/jkunert/archive/2008/08/21/differences-between-tdm-pbx-hybrid-pbx-ip-pbx.aspxIn the context of OCS 2007 voice deployments it is essential to understand the fundamentals of existing corporate telephone systems. This article describes on a high-level how a TDM (Time Division Multiplexing) PBX, a Hybrid PBX and an IP PBX look like.en-USCommunityServer 2.1 SP1 (Build: 61025.2)