The GPS units embedded in cell phones use satellites in geosynchronous orbit to provide precise locations. Ordinarily, people use this system to get turn-by-turn directions or figure out where they are. Cell phone GPS capabilities can also be used to locate someone if you have the right information.
Ensure the person has a GPS-enabled cell phone. Older cell phones can be tracked by other methods, but they are more difficult and less reliable than GPS methods.
Register the phone with a website such as AccuTracking. The site allows you to locate a cell phone and even monitor how fast the person carrying it is driving. You'll have to install the AccuTracking software on the cell phone before the site will be able to give you this information. From the phone you want to track, download the software from the AccuTracking website. After you've done so, you may log into the system and view information about the phone's whereabouts, accurate to within 100 yards.
Contact the authorities. In an emergency, police and other agencies can determine a person's location based upon where the person's cell phone "pings." Cell phones stay in constant contact with cell phone towers, and these records are maintained. Official agencies will be able to help you cut the necessary red tape.
Use a site such as Mologogo to find your friends. The Java-based application helps you stay in touch by posting your location in real time for your acquaintances to see. Just log in and look to see where your connected users are currently located. The map you see after logging in will allow you to get easy directions to meet up with the person for whom you're searching.
Employ a service such as Mapquest Find Me. For a small monthly fee, you can use your cell phone to search for people directly.