Text 30127, 99 rader
Skriven 2009-03-22 14:31:52 av Michiel van der Vlist (2:280/5555)
     Kommentar till en text av Robert Bashe (2:2448/44)
Ärende: Reactions
=================
Hello Robert,

On Sunday March 22 2009 11:31, you wrote to me:

 RB>>> All the cell phones I know of have what they call an IMEI, which
 RB>>> is the serial number of the phone, and is necessarily transmitted
 RB>>> along with the conversation since a relay station has to be able
 RB>>> to properly direct hundreds or even thousands of calls
 RB>>> simultaneously.

 MV>> You are confusing the serial number of the phone (IMEI) with the
 MV>> serial number of the SIM card. (SSN)

 RB> I know what you're talking about, and you may be right, but I still
 RB> think the IMEI is transmitted,

Oh yes, the IMEI is also transmitted during the handshake, but it is the SSN
that is used for the routing of the call ect, not the IMEI. When a phone is
paged, it is the SSN that is transmitted over the air and to which the phone
responds. Not the IMEI and not he phone nr either btw. The phone does not know
its phone number, the link between the phone number and the SSN is made by the
network adminstration.

 RB> since in England, phones reported as stolen are blocked with their
 RB> IMEI.

Yesm the IMEI can be used for identifying and blocking stolen phones. That is
in the GSM specs. But it is NOT used for the normal handling of calls and
therefore not "necessarily" transmitted as you stated. If the IMEI changes, to
the network that is as if you boufgt another phone and put your SIM card in
that.

 RB>  This is not a EU-wide thing, and I've only heard about it being done
 RB> in England.

In the beginning there was a plan for an EU wide database with stolen phones.
It did not come off the ground for two reasons:

1) No agreement could ge reached on who was going to pay for it.
2) Allegedly some administrative errors were made and duplictae IMEIs were
issued. Of course such a system of blocking stolen phones by IMEI will result
in disaster if uniqeuness can not be guaranteed.

 RB>>> In some cases, it's possible to change the IMEI (but is illegal),

 MV>> It is not illegal AFAIK.

 RB> Damn sure is in Germany and (naturally) in England.

Has anyone ever been convicted for changing an IMEI? If not, that law may be a
dead letter. Ould not be the first time that a law was made that has no
practical value because it is impossible to prosecute on it.

Maybe the Dutch law makers are a bit smarter than the German and the British.
here they realise that there is no point in forbidding something that you can
not prove has happened.

 RB> which naturally would make things more difficult for the snoops,
 RB>>> but is technically fairly complex to do so.

 MV>> With most phones it is not that hard...

 RB> Ever done it?

I have seen it demonstraed. It looked simple enough. Connect the data cable to
a loptop and some mouse clicks. Just as easy as removing a SIM lock.

 RB> I have, several years ago with an old Nokia. Unless you have the right
 RB> software (underground) and adapter, you can forget it.

Google is your friend.

Maybe some phones are bettre protected than others.

But to avoid being identified by IMEI ond can also buy a phone in a country
where they are not registered. (As in The Netherlands)

 MV>> ... but it is useless for the purpose of hiding one's identity as
 MV>> the SSN is used for that. The SSN can not be changed.

 RB> That's the simplest part. All you need is a SIM that is registered to
 RB> someone else. You can get such stuff in flea markets or through Ebay.
 RB> Not really legal, but it's done all the time.

Yes, but that way, you also use a different phone number.

 MV>> Changing the IMEI is usefull for hiding the fact that a phone is
 MV>> stolen. But of course that is something different.

Here in The Netrherlands one can anonimously buy both phones and SIM cards.
Fully legal, no problem. So buy a phone here. Of course you pay a lot more when
you use it in Germany due to the "roaming charge scam", but a criminal would
not have a problem with that I suppose...


Cheers, Michiel

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