A voice over Internet protocol communication system and method provides infrastructure components as intermediaries between networks, the components include multi-protocol session controllers and a multi-protocol signaling switch as well as a management system. The session controllers process calls and participate in the calls that flow through it. The session controllers process calls that are either at the edge of the network or at the core of the voice over Internet protocol network. The session controllers associate calls with one another in call peers for incoming calls as ingress call peers and for outgoing calls as egress call peers. A centralized database of call routing policies is provided to the session controllers. The session controllers provide cost management, topology hiding, and inter-working, or conversion, of calls from SIP networks to H.323 networks for both voice and video.