While most smartphones, theoretically, could get their time from GPS... do any use this method? As far as I know, my Android handsets get their time via NTP.
Ironically, often a misconfigured NTP server screws up GPS fixes (it somehow seems to be necessary for assisted GPS, which relies on the cooperation of the mobile network or Internet to faster acquire a GPS fix).
I think cell phones get their time from the tower, since they have to sync clocks with the tower to talk to it anyway, and the towers get time from GPS.
Ironically, often a misconfigured NTP server screws up GPS fixes (it somehow seems to be necessary for assisted GPS, which relies on the cooperation of the mobile network or Internet to faster acquire a GPS fix).
http://stackoverflow.com/questions/8308412/gps-how-ntp-time-...