GPS positioning uses a three-dimensional triangulation method (called trilateration) to determine the location of the GPS receiver. Knowing the distance and location of multiple GPS satellites, the receiver can mathematically calculate the intersections of three (or more) spheres to determine its own location, using geometry in three dimensions. Trilateration is explained at http://en.wikipedia.org/wiki/Trilateration.

There are 200 million Blackberry phones which have been shipped. All of them have GPS capability. Some of the newer models have the ability to track the phone's location and provide coordinates to applications which need that information using trilateration rather than GPS. Trilateration is less accurate but saves on battery life.

It's done with trilateration. Read more here http://hubpages.com/hub/How-Does-GPS-Work-In-Cell-Phones

GPS systems use the twenty-seven satellites that orbit the earth. The GPS receiver uses a mathematical equation similar to trilateration. The GPS receiver uses four or more of the satellites that are constantly orbiting the earth and use the information received to find it's location.

Cell phone gps tracking software is software that trilaterates (or triangulates) your location using 3 satellites in space. You can track someone yourself, if they have gps on their phone, using trilateration.