Abstract: A system and method for enabling a first device that may optionally roam between at least first and second wireless networks to communicate with a second device that may optionally roam between the at least first and second wireless networks. The devices are preferably registered to each network in which the device may roam. A routing switch first transmits a data message to the receiving device at the last known location of the receiving device. If a negative acknowledgement is received, the message is routed to all other networks to which the receiving device is registered, either serially or in parallel, depending upon the configuration of the transmitting network. Routing devices and/or gateways are preferably provided for each network to provide any required protocol and/or message format conversions.