Apparatus for mediating between a cellular telephony network and a wireless LAN, comprises a first adaptor for allowing signal exchange with the cellular telephony network, a second adaptor for allowing signal exchange with the wireless LAN; and a presence tracker associated with the adaptors for obtaining...http://www.google.es/patents/US20060052113?utm_source=gb-gplus-sharePatente US20060052113 - Roaming presence and context management
