Although the technology exists to be able to track people through the signal emitted through their mobile or cell phone, the technology is not available to the general public. The police, army or government will have the facilities to be able to use the GPS or network signal on your phone to triangulate your position on the earth to within about 15 meters. In some countries, for example the United States, a warrant must be obtained before a mobile phone can be tracked. The technology works when your phone's signal is in operation. The phone will be connected to a network of receivers and satellites around the Earth. The technology will then allow the operator to see which satellites and receivers are being used and use this to plot or 'triangulate' an estimated position on the Earth. The longer the signal on your phone is connected the more accurate the triangulation will be as it will 'hone' in on your location based on signal strength. With regards to your question, I would ask in return why you would want to find someone's exact location. The technology is limited to government and law enforcement agencies to be able to aid in the capture and prevention of criminals. By opening the technology up to the general public anyone would be able to be tracked at any point without accountability. Privacy and privacy laws are very important in most, if not all, countries worldwide and the use of this technology to 'spy' or track people without accountability or authorized use could be seen as a breach in people's right to privacy. It could be seen as a very untrustworthy existence to be able to search and locate anyone anywhere. Take celebrities as an example, the ability to track them would be an abuse of their privacy and they would never be left alone.
