Do Phone Records Record Location of Mobile Phone?
July 15, 2009 7:08 PM   Subscribe

I'm writing a crime story and need to know the following detail about phone records: Let's say I live in Dallas, but while I'm visiting New York I call Joe using my mobile phone. Because there has been a crime committed, the police have subpoenaed Joe's phone records. MY QUESTION: When they see the record of the call, will the police know that the phone call originated from New York instead of Dallas?
posted by bagadonuts to Technology (12 answers total) 1 user marked this as a favorite
posted by Jairus at 7:10 PM on July 15, 2009

Yes. I'm sure you've heard the phrase "triangulate". This is what cell phone companies do (did) to find out the physical location of the cell phone (by using multiple antenna to pin down a general location of where a call originated from).

When you make a call in dallas you are using different antenna to connect to the network. That is logged.

I don't know the communication between the police and cell phone companies...but I can't imagine that the police would think that a cell phone with a dallas number is ALWAYS in dallas.

Hope that helps.
posted by hal_c_on at 7:12 PM on July 15, 2009

Yes. My friend is a lawyer and has subpoenaed such records. They will more-or-less know where the phone is. Moreso in highly populated/covered areas, less so in rural areas.
posted by jessamyn at 7:16 PM on July 15, 2009

Yes. When Mark Sanford went AWOL from Columbia, SC recently, cops looking for him traced his phone to Atlanta. (where it vanished because he left the country) A guy in NYC recently got done for murder in part because records showed he used his phone near the body's dump site.
Here's some info about tracking a phone's location.
posted by CunningLinguist at 7:26 PM on July 15, 2009

As others have stated, cell tower information is certainly logged by the cell phone companies. However, I think that law enforcement might have to specifically request it (though by now, standard forms are probably used). If you just subpoenaed something as vague as "cell phone records," you might get something that looks like a phone bill, which probably wouldn't have cell tower information.
posted by Conrad Cornelius o'Donald o'Dell at 7:44 PM on July 15, 2009 [1 favorite]

To those who have answered yes, are you sure that Joe's phone records would mention the location of bagadonuts's phone, assuming they used different carriers?
posted by kidbritish at 7:52 PM on July 15, 2009 [1 favorite]

The answer would be unequivocally yes if Joe's phone was under surveillance (wiretap). The phone records themselves will usually (always?) identify the home and serving switch. This means that not only would the Police know you made a phone call from New York, they would also know that your home area was Dallas. Also, the cell tower id is part of the raw phone records (called Call Detail Records, aka CDRs). When law enforcement subpoenas for call records, the phone company would provide them with the CDR information, which has more information than what goes on billing statements.
posted by forforf at 8:10 PM on July 15, 2009

Having called cell phone records in a trial (albeit in Canada), I can say - it depends. Mostly it depends on how quickly the police know that the phone call in Joe's records are important. That will get them your phone number. Then they will get YOUR phone records, if they think your call is an important one. If that has all happened in a short enough time period that your carrier still has the call logs (as opposed to the billing logs - which will simply show you called Joe, and the length of the call - which are available for a MUCH longer time), THEN the police can use the cell tower data to get a rough idea of where you were when you called Joe. However, if they are only looking at Joe's records, where you called from will not show up.
posted by birdsquared at 8:12 PM on July 15, 2009

As I understand it, the main Call Detail Record for each side of the call will contain a pointer to the other carrier and also a pointer to the local switch that originated or received the call. If the switch is a cellular one (MTSO) it will maintain its own database of cell tower data for that call. So in order to capture the full path of the call you'd need to query up to 4 databases.
posted by scalefree at 8:41 PM on July 15, 2009

When I had a post-paid mobile phone, the cell tower through which the call originated was always listed on the bill along with the number called, duration of call and charges, so it was part of the billing records here.
posted by Lolie at 8:47 PM on July 15, 2009

Can they tell it originated in New York? They can nail it down to the cell tower. Italian police did it and charged several CIA agents with kidnapping for an extraordinary rendition which occured there. Any of those agents ever show up in Europe, they are arrested.
posted by Ironmouth at 10:12 PM on July 15, 2009

A little more on triangulation:
As far as I know*, cell-phone triangulation does not result in an exact location - rather a "shape" that represents the likely area that the phone is in. Of course, you can find the centre-point of that shape if you want a single location

Also note that the size of the shape is influenced by the number of cellphone towers and the distance you are from them. ie. The location of a mobile phone in the middle of the forest will be far less accurate (many kilometres across) than the location of a mobile phone in the centre of the city (a couple of hundred metres).

* I work for a company that does cellphone triangulation-ey stuff, but I'm not completely clued in about all the different types of triangulation systems available and if they all offer the same levels of detail.
posted by abstractdiode at 10:14 PM on July 15, 2009

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