A communications system connecting mobile subscriber devices to at least one of a PSTN and a plurality of PBX networks comprising a plurality of network interface units coupled to one of a PSTN and a PBX network, each of the plurality of network interface units having a predetermined coverage area; at least one mobile subscriber device, the mobile subscriber device assigned to one network interface unit considered a home network interface unit, and the mobile subscriber device receives a port assignment through the home network interface unit from one of the PSTN and the PBX network coupled to the home network interface unit, the PSTN port assignment determining the mobile subscriber device directory number, and the PBX network port assignment determining the mobile subscriber device extension number; a wireless access unit coupled to each of the plurality of network interface units and providing wireless connection between the network interface unit and a mobile subscriber device within the coverage area of the network interface unit; and a programmable cross-connect device connecting the plurality of network interface units and dynamically cross connecting calls between the home network interface unit of the mobile subscriber device and a visited network interface unit as part of call origination and termination process, the visited network interface unit covering a geographic region within which the mobile subscriber device is roaming.