How do the cops trace a payphone call? (nm)
Coming from Technical Support with one of the top 3 wireless carriers, I can tell you this :
Depending on which way the call trace is being done, it usually takes all of 2 to 5 seconds to get the information. You also need to know which way the trace is being done, incoming or outgoing. It's a little more detailed below. I hope this helps. my email is listed on my imdbpro.com profile. Send me an email if you want.
*** FYI : Most wireless and landline carriers use the term CTRAI or CT when referring to a call trace. It's best to keep this out because only network engineers would be familiar with this term. ***
(1) What is call trace ? Allows a carrier to determine the origin and/or destination of a call. To track the progress of call over multiple platforms. To perform maintenance on the network.
Movie Hype about Call traces.
(1) Any movie stating it takes 15 to 60 seconds for a call trace is merely for dramatic purposes.
(2) Any movie stating all you need is the phone # to run a Call Trace is true for landline phone numbers, but not always true for wireless.
(3) What's needed for a call trace is as follows :
<a> Mobile directory number (MDN)
<b> Mobile subscriber identification number (MSID/MIN)
<c> International mobile subscriber identity (IMSI) if it's a GSM system
<d> The service switch (MSC)
<e> The home switch (MSC).
See [*note] for explanation.
(4) Any movie that states the wireless phones needs to be on in order to do a call trace is correct. However keep in mind that most, if not all, wireless carriers keep a call log of calls made to and from wireless number. All that needs to be done is the police would need a subpoena to see the call history. This information is usually stored for up to 1 - 3 months. Either way, it would give a general location for wireless calls and exact location for landline calls. Wireless locations are usually within 1 to 5 miles max. If more is needed than one would need at least 3 calls to triangulate the area.
(5) Any movie that states the call has to be answered to start a call trace is merely for dramatic need. When running a call trace for a call placed from a known number, the call trace can start as soon as the subscriber presses the Send, Talk, or whatever key is on the wireless phone. So, lets say you have a cop or whoever that wants to find out where a person is and knows the person phone number, as soon as the cop places the call the trace starts and would show a general area for wireless and an exact location for landline. It would not matter if that person answered the phone or not. Now, lets say your cop or whoever wants to trace an incoming call, than a reverse call trace starts as soon as tge cop or whoever answers the phone. Again, the call trace would give a general location for a wireless phone, because it's mobile, and an exact location for a landline phone.
[*note: The reason being , lets say in your movie the police want to trace a call to or from a wireless number. They would first need to know what carrier it belongs to. This is done by looking up the first 6 digits of any phone number, sometimes it may take the full number (see *note). The first 3 are commonly known as the area code or NPA, which gives the state. The second 3 are commonly known as the exchange or NXX, which gives the city.
If a carrier still has not been determine than last 4 digits are needed. Due to Line number portability (LNP), customers can take their number anywhere; landline or wireless. The means, the carrier does not own the full block, used to describe 10 to 1000 numbers (ex: block of 10 numbers would be NPA-NXX-0000 to NPA-NXX-0009, block of 1000 would be NPA-NXX-0000 to NPA-NXX-0999), or range, used to describe 10,000 numbers (ex: range would be NPA-NXX-0000 to NPA-NXX-9999). The last 4 digits are referred to as the destination, XXXX, range or block; however this is not common knowledge to the public. ]
One more thing to add :
calls to 911 are traced the same way. The information transmitted on any call trace, landline or wireless is
(1) For wireless -
- esn ( Electronic Serial Number)
- IMSI ( see above)
- MDN ( The phone number)
- MIN/MSID ( see above)
- Location ( General anyway as long as the call remains active )
(2)
- MDN ( The phone number)
- Location ( As long as the call remains active )
Things to keep in mind
- For wireless call traces the call has to be active, not necessarily answered.
- All cell phones have what is called a transceiver ( Transmitter/receiver)that sends and receives signals to the network. So in actuality the cell phone just needs to be on and the last known location, more commonly known as the last registration can be found all the down to the cell site and sector.
- All cell phones do what is called autonomous registration. This means the cell phone sends request to the network to update it's location. The purpose is to ensure proper call routing and feature updates ( like voicemail indicator, text messages, picture mail, etc. )
Question:
With cells, generally how big an area can the call the traced to? If the call comes from a city, that could include a lot of people. The country, a lot of area. Right? Wrong?
Answer:
I'll try not to get too technical like I did before. To answer your question :
With cells, generally how big an area can the call the traced to?
A couple things I would suggest figuring out:
(1) Is the person standing in one location ?
If they are standing in one location, the call trace would only show the serving msc ( which can cover over 100 miles), the cell site being used ( which depends on where the person is :
City - A cell site generally covers one to two city blocks. The reason too many obstacles ( tall buildings, etc.) that block the signals.
Suburbs - A cell site generally covers one to five miles. The reason less obstacles.
Rural - About five to ten miles. The reason even less obstacles.
Boondocks ( ex: middle of Nebraska) about fifteen to twentyfive miles. The reason there is absolutely nothing there to block the signal from the cell site.), the voice channel being used.
Ex:
Let's say your character is in the city and a call trace is done. The trace would give on average a one to two city block radius of where the person is. The cool thing that most people don't know, any major building such local or state government, major corporations, or shopping malls, would have a cell site in that building. So if your character is in the Empire State building the call trace would suggest that.
Ex #2:
Let's say your character is in the mountains. This is harder because no wireless carrier puts cell sites in a mountainous region because of the terrain. So if your character is located in the Rockies, it's not going to be believable. The character would have to travel down the mountain in order to get a signal.
Think of it like this, the great the population the great number of cell sites and vice-versa, smaller population the smaller number of cell sites. It costs a few million dollars for a cellular carrier to put up a cell site. It's not going to benefit the carrier to put up a cell site if they can't get it or if it's going to be in an area that is not going to generate revenue equal to or more than the cost of building it.
(2) Is the person on the move ?
If the character is on the move than the call would be handed off from cell site to cell site. The direction and route would easily be seen regardless of the characters location, well minus the character being in the mountains.
Ex #1:
Let's say your character is traveling on a major highway. The trace would then show the direction the character is traveling and would possibly the mile marker they are at. On major US highways, due to 911 regulations, most cell site are associated with a mile marker to ensure a faster response if it is a 911 call.
Ex #2:
Same would be true if your character is in a city. The trace would show the direction and street the character is on within one to two blocks.
The best way to get an idea of what I'm talking about is to go to
www.cellreception.com. It should give you an idea of the radius I'm talking about. If you feel comfortable enough, give me an email address where I can send more detailed pictures so you can get a better idea.
