A source for obtaining the location of a mobile device. Satellite-based GPS is the major location provider. Assisted GPS (A-GPS) uses the cellular system, which knows where a phone is at all times, and cellular base stations report their cell location number (CELL ID) to pinpoint a device. If users do not opt out, passive location providers record the built-in network IDs (MACID) from every local mobile device via Wi-Fi. See
MAC address,
mobile positioning,
GPS and
A-GPS.