Tracing a call earlier was not possible. Over the past few years, technology has developed so much that we can now track down any phone or trace any phone call. Tracking down a landline is easy as they are fixed and permanent.
However, in the case of mobile phones, it is very difficult to narrow down the location because they are portable and always on the move.
Following the September 11 terror attack, it has become important to trace and track down phone calls of the terrorists so as to prevent these kind of attacks.
Phones are now traced using a process called triangulation. Prior to making a phone call, the phone sends a short message or a 'ping' to the nearest network masts or towers. These pings are sent in a bid to make their presence felt.
Subsequent to the pings being sent, the phone becomes active and phone calls can be made through it. These pings are sent in each and every possible directions so as to reach as many network masts as possible in the vicinity.
If the network masts are closer to the phone, then the signal strength will be higher. Though the pings are sent to many towers, the closest two towers are considered during the process of triangulation. This is determined through the signal strength.
This process is very useful in tracking down any phones. Even if the exact position of the caller cannot be calculated, it gives us a idea in general as to where the person is.
The exact position cannot be calculated because the caller will not be stationary i.e. will always be on the move. Further investigation can lead to tracking down that particular person.
Despite the fact that this technique is the most widely used form of tracking down a phone, software such as Google Latitude can also help you determine the whereabouts of your friends.
Save for this, that person must be a 'latitude' user. This software gives the exact details of the position of the person i.e. where he has been and so on. On the other hand, this software helps you track down the people who you already know and hence it may not be of much use.
To precisely track down any unknown person, other software has to be considered which is not easily available unless your reason is genuine. Software for this kind of applications is not easily available for the reason that it is an invasion of one's privacy.
If it is for tracking down a criminal or else if your reason is genuine, in that case the software can be obtained from the concerned authorities. Consequently, phones can at present be tracked with no trouble and quickly.