How to Identify Mobile Phone Calls at the Location

[jonovid]

the problem
is it possible to electronically identify a mobile phone call at its location?
or with in 5 to 10 meters of the phone itself.
by detecting the IMSI number or home location register HLR number when the phone is used.
 a subscriber ID calling the network.

for example an intruder uses a mobile phone at the location when breaking and entering.
or example a classroom.  students use mobile phones in class.  but identifying who it is?
or example drug dealing seen on CCTV in the street and mobile phones are used.

vehicles have registration & VIN numbers, one is visible to the public the other is not.
so do mobile phones have an electronically visible or unencrypted call number when a call is made to the network?
if so, can this be used to Identify the particular Mobile Phone in use?

[NiHaoMike]

It used to be that you could sniff for Wifi MAC addresses but that no longer works due to a countermeasure against marketing companies trying to do just that.

[soldar]

It used to be that you could sniff for Wifi MAC addresses but that no longer works due to a countermeasure against marketing companies trying to do just that.

What? Maybe I am misunderstanding but this makes no sense to me.

Phone calls are not WIFI so I cannot see how it is relevant and I have no idea what marketing companies were trying to do but as far as I know MAC addresses are still transmitted in clear and visible. I cannot see how it could be otherwise.

[Someone]

It used to be that you could sniff for Wifi MAC addresses but that no longer works due to a countermeasure against marketing companies trying to do just that.

What? Maybe I am misunderstanding but this makes no sense to me.

Phone calls are not WIFI so I cannot see how it is relevant and I have no idea what marketing companies were trying to do but as far as I know MAC addresses are still transmitted in clear and visible. I cannot see how it could be otherwise.

99.99% of people leave their wi-fi and bluetooth on at all times, which can be fingerprinted. Requires countermeasures like MAC randomisation:
https://www.juniper.net/documentation/us/en/software/mist/location-services/topics/concept/mac-randomization.html

[Halcyon]

I don't think there is a simple way to be able to track unique identifiers from the cellular baseband radio, even for law enforcement this required fairly specialised equipment.

As others have pointed out, you could look for either WiFi or Bluetooth MAC addresses from handsets, but modern Android and iOS randomise those MAC addresses, so the same device won't show the same address constantly.

Phone calls are not WIFI

This is another topic, but some providers actually do route standard voice calls via WiFi by default (Telstra in AU for example). This is known as WiFi Calling and has been available on most mainstream handsets since about 2016/2017.

WiFi SMS is a thing as well.

[soldar]

99.99% of people leave their wi-fi and bluetooth on at all times, which can be fingerprinted. Requires countermeasures like MAC randomisation:

Huh. I had not thought of that. I guess I am part of the tiny percentage who switches WIFI (and BlueTooth) on only when I am using it, mainly to save battery and also resources. Anything I am not using is not running.

[tszaboo]

About 15 years ago the company I worked for was making a call detection device for prisons. So we wanted to detect the inmates making phone calls. They obviously shouldn't have access to phones. With 2G this was possible with a simple antenna, and a envelope detector, at the beginning of the call, the phone transmits at max power to determine how much power to use. Measure RSSI and then reduce the TX power to keep acceptable link budget.
With LTE it's a whole different issue. Browsing the web isn't different from a phone call, it's all data. It's not impossible, but I don't think you will have access to the software to do it. Or if you do, then you already know how to do it, and you wouldn't ask it on a forum.

[indeterminate]

Your not even going to know if a particular phone is transmitting anything.
all the phones on a particular network are going to be shearing the same 10,20> mhz carrier
unless you know the speeder code being used between the base & handset its just going to be wide band noise.

[mendip_discovery]

Yes you can, but the legality of it would no doubt end in a prison sentence in most countries.