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Does swapping a SIM card work?

By Tink! ·
In the movie 12 Rounds, the villain continually eludes police tracers by swapping out the SIM card in his cell phone.

Was wondering if that could really work.

NO, I'm not considering it for real-life, I'm writing a story and need a way to avoid being traced in a cell-phone conversation. Several times.

In case you're interested, the story is here:

Feel free to read and comment. :)

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by cmiller5400 In reply to Does swapping a SIM card ...

If they tracked on "hardware address" (IMEI), then it wouldn't work. The SIM card (IMSI) stores only the subscriber information, so theoretically, you'd only change the phone number not the "address" of the phone.

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My intial instinct would be no...

by NotSoChiGuy In reply to Does swapping a SIM card ...

...since not all Telecom providers require SIM cards. I'd imagine they're getting tracked by either the GPS or IMEI information.

However, I am not a cellular expert by any means, so I could be as wrong as a 'S' is crooked.

As for the story, I'll try and give it a read this weekend; provided the teething baby settles down enough for it to happen!

EDIT: In terms of the story, you could always have the perp save his contacts to a SD card, and just plug that into a variety of disposable phones as he/she goes; assuming the saved numbers is why the phone itself wouldn't be getting pitched.

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Ok so how DOES police tracing work?

by Tink! In reply to My intial instinct would ...

on the movies they either trace the actual phone# or the cell phone location based on what towers it's bouncing off of.

What's the low down on HOW that sort of tech works?

Actually it's not a criminal or villain that needs to be untraceable. It's a good guy(s) that needs to hide from a government research agency.

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If they are tracing by active transmission...

by seanferd In reply to Ok so how DOES police tra ...

then all the phone user has to do is end the call. The character would probably have an idea of how long that would take, on average. Just keeping calls short would work.

Disabling the GPS/911 feature would prevent locating the phone through the GPS-enabled location system.

For the truly paranoid types, they would have the GPS-related hardware bits damaged, assuming this doesn't otherwise break the phone.

I suppose a case could be made for having the cellular provider hacked so that searches for the phone would be misdirected.

(No research done here.)

A quick glance at the story - looks interesting.

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Why not

by SKDTech In reply to If they are tracing by ac ...

VoIP transmissions over wifi and routed through a TOR network. Between short calls and the difficulty of backtracing the call through TOR he could bounce from hotspot to hotspot remaining several steps ahead.

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by seanferd In reply to Why not

I was wondering about the possibilities of VOIP in itself. I'm just not well-versed enough to know whether one could be tracked through the VOIP account, and how a phone call would leave the VOIP network at the other end in the case that the call was to a non-VOIP phone.

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Not quite right

To locate the phone, it must emit at least the roaming signal to contact the next nearby antenna tower, but the process does not require an active call.

The following is from my notes, not sure where I got them though:

Locating systems can be broadly divided into network based, handset-based, and hybrid:

Network-based techniques utilize the service provider's network infrastructure to identify the location of the handset. The advantage of network-based techniques (from mobile operator's point of view) is that they can be implemented non-intrusively, without affecting the handsets.

Handset-based technology requires the installation of client software on the handset to determine its location. This technique determines the location of the handset by computing its location by cell identification, signal strengths of the home and neighboring cells or the latitude and longitude, if the handset is equipped with a GPS module. The calculated location is then sent from the handset to a location server.

Hybrid-based techniques use a combination of network-based and handset-based technologies for location determination. One example would be Assisted GPS, which uses both GPS and network information to compute the location. Hybrid-based techniques give the best accuracy of the three but inherit the limitations and challenges of network-based and handset-based technologies.


Cell Identification - The accuracy of this method can be as good as a few hundred meters in urban areas, but as poor as 32 km in suburban areas and rural zones. The accuracy depends on the known range of the particular network base station serving the handset at the time of positioning.

Enhanced Cell Identification - With this method, one can get a precision similar to Cell Identification, but for rural areas, with circular sectors of 550 meters.

U-TDOA - Uplink-Time difference of arrival - The network determines the time difference and therefore the distance from each base station to the mobile phone.

TOA - Time of arrival - Same as U-TDOA, but this technology uses the absolute time of arrival at a certain base station rather than the difference between two stations.

AOA - Angle of arrival - AOA mechanism locates the mobile phone at the point where the lines along the angles from each base station intersect.

E-OTD - E-OTD is similar to U-TDOA, but the position is estimated by the mobile phone, not by the base station. The precision of this method depends on the number of available LMUs in the networks, varying from 50 to 200 m.

Assisted-GPS - A largely GPS-based technology, which uses an operator-maintained ground station to correct for GPS errors caused by the atmosphere/topography. Assisted-GPS positioning technology typically falls back to cell-based positioning methods when indoors or in an urban canyon environment.

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You will have Tink!

by santeewelding In reply to Not quite right

Writing like Tom Clancy, if she can get by all the other stuff.

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by Tink! In reply to Not quite right

Definitely what I was looking for! Now to sort it all out in my brain.

Thanks for this Michael!

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Awesome, as always.

by seanferd In reply to Not quite right

That is a fantastic bit of information.

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