Forget everything television and Hollywood has taught you about tracing a phone call. Not since the 1980s has the incoming call needed to last three minutes or longer in order to trace it successfully. That's when phone companies changed from using operators and switchboards to using electronic switching mechanisms, making a caller's name and address available instantly. The same technology that is used to provide customers with Caller ID is used by the phone company and by law enforcement to trace phone calls. In the event you want to trace a call but do not have the assistance of law enforcement, you can dial 57 and that triggers a request to the phone company to trace the call. There is usually a fee for this service and it can take a day or more. You can also identify the last number that has called your number by dialing 69, though this method does not work with blocked or unlisted numbers. If you have been receiving harassing phone calls, you can request the phone company's help to trace the calls and contact law enforcement for you if there have been several of these type of communications. Call your phone company and ask to speak to the Harassment Desk. Explain your problem, document the dates and times of the calls, but expect to wait several days or any action.
Cell phone calls are traced by using two technologies: satellites and cell towers. Newer cell phones are equipped with Global Positioning System (GPS), which works by measuring the time it takes a radio signal to travel between the satellite and the phone. This time is then translated into a location, a process that is so quick it's almost instantaneous. The downside of GPS tracking is it doesn't work well indoors or during some inclement weather and uses a lot of battery power. Cell tower technology works by locating a phone in relationship to the nearest towers. A cell phone is constantly searching for the strongest signal and this search goes out in the form of pings, or radio signals between the towers and the phone. These pings are triangulated and a location is calculated, with some such calculations being able to identify a location within 300 feet. This process can take up to 30 minutes or longer.
Using Internet Databases
An Internet search will reveal many services, called Reverse Lookup, that will track phone calls for a fee. This is not a trace per se, but will provide you with the name and address of the caller, as well as their call history and phone service provider. These services offer a search window for you to enter a phone number and then can provide a full report via email or online download. The accuracy and price of these services can vary widely. The most reputable ones use the same databases as police and the FBI and offer sample reports for no charge.