How To: How Triangular Phone Tracking Works (How the FBI Traces Cell Phones)

How Triangular Phone Tracking Works (How the FBI Traces Cell Phones)

How Triangular Phone Tracking Works (How the FBI Traces Cell Phones)

Hello again, my fellow hackers! Today, I will explain to you how the FBI can trace any mobile phone number to an exact location on US territory. This method is called "triangular lookup" or "triangular trace", or just "triangulation".

This way of tracking requires direct access to the mobile cellphone provider's systems, so it isn't something that is available for the average hacker. But since many of you might be planning on joining the agency responsible for intelligence of your country, it might be VERY vital to know how triangulation works!

So, Let's Begin!

To better understand triangulation, let's look at the shape of a cellphone tower. Take note that it has the shape of a triangle:

Image via

Each side of the triangle is called a sector. These sectors are labelled by the Greek letters alpha, beta, and gamma (a, ß, Y). Within each sector, the tower can see how far away a connected cellphone is. This allows it to "trace" the cell phone: by detecting which sector it is connected to, and how far away the cellphone is. Here is a representation of these sectors, with the cell phone tower being in the middle:

Image via

Now, let's say our target is connected to sector gamma, and is in the number 4 range. Then we know that the cellphone is somewhere in the by yellow marked area:

Image via

I think you get the idea. Let's move on to what happens when we use 2 towers!

When a cell phone is connected to 2 towers that overlap each other at the same time (this must be the case), we can further increase our accuracy in tracing the phone. The cell phone is connected to the blue tower's sector alpha and is at the 5'th band (5 miles) in distance, while it is also connected to the orange tower's gamma sector and is in the 4'th band of distance (4 miles) of the orange tower, we can trace the cell phone really accurately by comparing the 2 results of the 2 towers, like shown below:

Image via

Now, if a 3rd tower is brought into play, we get what is called a "triangulation". In this case, we can trace the cell phone REALLY accurately! Let's see what happens when we bring a 3rd tower in:

Image via

As you can see, the mobile phone is again within the red circle. If it moves to the left, it enters the green tower's band 6. If it moves right, it enters the green tower's band 4. If it moves down, it enters the green tower's gamma sector and also enters band 4 of the blue tower. I think you all get the idea.

Only the government or the mobile provider could pull off a triangulation, unless a hacker has compromised the system of course. This way of tracing is very reliable and is used a lot by the FBI, because the target doesn't need to have GPS or anything else on, it just needs to be connected to a cell tower.

Triangulation is almost always possible in urban areas, because the towers are close to each other, but it is less common in rural areas, where the towers are more apart than in a city.


That's it, my friends and fellow hackers! I'm sorry for being sloppy in this article, but I have A LOT of work for school and I wrote this article quickly.

I just explained how triangulation works, but I have no idea how to actually perform it, since I haven't gotten the chance yet to actually try it myself. Maybe this is something our more experienced admin OTW can cover?

If there is anything you don't understand, feel free to comment or PM me!

See you later on our fresh IRC channel!



Great article!

Diagrams are great! Easy to understand. +1

I understand how it work's but have a question. Would it be impossible to trace if you put a cell phone right under the tower and use call forwarding? Kinda like what Liam Neeson done in Taken.

This is just plain awesome. Not the fact that the FBI triangulates calls, but the article itself. Fantastic job.

great tut, +1

So the towers keep our information like that.

Reminded me of GPS technology, just the lines have a width and are divided in 3 parts. And without the complications due to acceleration of earth.

Can it be faked, like GPS?

-The Joker

The antennas don't keep your information. The antennas work like a sort of relay between the service provider, other antennas and mobile devices. Usually the antennas have a device called a BTS (base transceiver station) which is a radio equipment that bridges between the common user and the communications provider. The BTS is connected to a BSC (base station controller), its like a manager for the BTSs. This device is also responsible for a procedure called handover, its when you move from one antenna's area to another antenna without loosing connection.

The information regarding user data might be in the MSC (mobile switching center), its what connects the user to other users in the same network or others.

I hope it was helpful.



Nice tut, simple and direct. Whats used here is pure and basic mathematics. Three points (x,y,z) defines a point in space. And measuring the signal strength between the cell phone and those three points, you get a location.

Middle school maths for the win!


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