> > The phones do not have actual GPS receivers > > built-in: it's some funny business with cell tower signals, and they > > call it "GPS". Actually, it's called aGPS (assisted GPS) and uses time delay and triangulation by the towers as well as satellite signals (which are presumably relayed, with or without processing, from the phone to the tower since GPS is a one-way down signal). http://ezinearticles.com/?GPS-Cell-Phones&id=52208 If I recall, the original question was how to use this to find a lost dog. According to http://www.travelbygps.com/articles/tracking.php Location-Based Services (LBS) providers have agreements with the wireless network carriers to receive data from a cell phone and make it accessible to you via an Internet web site or call center. Most all LBS providers will be able to tell you the approximate last known location, but beyond that, services offered will vary, depending on the type of cell phone and the capabilities of the service provider. Sounds like it might work, until the dog decides to go for a swim, but I assume the original poster wanted some kind of DIY solution rather then buying another service.