Integration of the cellular network with an IP based network is disclosed. An integrated IP/cellular network can route packetized voice and data together in a more efficient manner. The present invention integrates IP based standards for a cellular IP solution with cellular centric vs. IP message gateway as the demarcation point. However, the present invention also provides support for cellular unique features for better performance. Multiple architectures are proposed to ease migration to a combined network as well as to show the various levels of support provided.