Methods and apparatus are disclosed for reducing wireless telecommunication costs for enterprises having a plurality of PBX-equipped sites, connected by either a public network ( e.g ., the PSTN, the Internet, etc .), a private network ( e.g ., leased lines, a virtual private network [VPN] over the internet, etc .), or some combination of public and private networks. In particular, the illustrative embodiments of the present invention attempt to reduce telecommunication costs by advantageously routing calls from an off-premises wireless terminal belonging to the enterprise via one or more of the enterprise's private branch exchanges. The present invention is especially advantageous in that it can reduce telecommunication costs for calls from an off-premises wireless terminal to any type of destination: another cell phone, a wireline terminal, a private branch exchange, etc .