A wireless telecommunication device, such as a cell phone, is coupled to a source of digital data which may comprise a GPS receiver. In one embodiment, a GPS receiver and inband signaling modem are integrated into the cell phone battery pack. A pushbutton on the battery pack is actuated by a user to...http://www.google.es/patents/US6681121?utm_source=gb-gplus-sharePatente US6681121 - Circuitry for activating a modem in a cellular telephone
Circuitry for activating a modem in a cellular telephone
