A mobile application gateway for connecting devices on a cellular network with individual networks, such as enterprise voice and data networks and/or residential networks. The effects of the present invention are far reaching in terms of transferring effective call control from the cellular network into the control of the individual network such as the enterprise, and enabling new business models for the purchase of cellular service from a public cellular carrier by an enterprise. The invention may consist of a primarily of core network and services components based on the IMS network architecture, and is backward compatible to support legacy systems in place in current telecom and data networks.