How Google Maps determines your location

These guys at Google are S-M-A-R-T-T.

Wireless phones can make and receive calls because they are connected over the air to a nearby cell tower. The phone knows the ID of the cell tower that it's currently using...

...If the phone has GPS, the Maps application on the phone sends the GPS coordinates along with the cell ID to the Google location server...

...Over millions of such updates, across multiple phones, carriers, and times, the server clusters the GPS updates corresponding to a particular cell ID to find their rough center. So when a phone without GPS needs its own location, the application on the phone queries the Google location server with the cell tower ID to translate that into a geographic location, i.e., lat/long coordinates. Nifty, huh? We think so.

Very, very slick. GPS-equipped phones send a data pair (GPS location as well as cell tower ID) to Google. That data is saved in a database. When non-GPS-equipped phones send their cell tower ID, Google then utilizes the database to compute GPS location.

Consider it crowd-sourcing for location.

The reconstituted Ma Bell (let's just call them AT&V and wave a thanks to the FCC) isn't real pleased.

The telephone carriers' monthly charge for GPS services -- yes, a monthly charge for receiving signals from government-owned satellites! -- isn't nearly as compelling these days.

So, give thanks to Google. They even modified their logo to celebrate Independence Day.