A method to remotely determine a location of a mobile unit without intervention by a user of the mobile unit is provided. The mobile unit may receive a location query, download location data from a GPS, and transmit the location data via a wireless telecommunications network. For example, a call center may initiate a location query using a voice channel call to the mobile unit. In addition, the mobile unit may select a mode of communication from a number of alternative modes of digital wireless communication based upon a determined characteristic of the transmission mode. By way of example, the determined characteristic could be a transmission speed, cost of transmission, or signal strength of the selected communication mode. Furthermore, the unit may be a battery pack or other accessory device attachable to a wireless telephone handset.