Text 30209, 123 rader
Skriven 2009-03-24 01:31:45 av Michiel van der Vlist (2:280/5555)
     Kommentar till en text av Robert Bashe (2:2448/44)
Ärende: Reactions
=================
Hello Robert,

On Monday March 23 2009 08:30, you wrote to me:

 MV>> Oh yes, the IMEI is also transmitted during the handshake...

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

 MV>> Yesm the IMEI can be used for identifying and blocking stolen
 MV>> phones. That is in the GSM specs. But it is NOT used for the
 MV>> normal handling of calls and therefore not "necessarily"
 MV>> transmitted as you stated...

 RB> So how do these two statements of yours agree?

You have to go back to your original remark that I commeted on:

 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.

Note that I commented on the "to be able to properly direct.." part

 RB> The IMEI is transmitted at least in the handshake, which is necessary
 RB> to even start a transmission.

Yes, the handshake is necessary....

 RB>  But it is not "necessarily" transmitted?

The IMEI is not necessary information to set up or maintain the call. It is
transmitted along with other information, but nothing is "done" with it. Any
number will do, presumably including zero.

 RB> It has to be one OR the nother, not both.

Both. It is transmitted in the handshake, but it is not needed to make the
call.

 RB> And in view of the fact that stolen phones are blocked using the IMEI
 RB> in England, I would tend to stick to what I already wrote. I never
 RB> wrote that the IMEI was _continuously_ transmitted, since that's
 RB> naturally unnecessary, but that wasn't the point.

It was this part after "since" that I think is wrong:

 RB>>> and is necessarily transmitted along with the conversation since a
 RB>>> relay station has to be able to properly direct hundreds or even
 RB>>> thousands of calls simultaneously.

[ changing IMEI ]

 MV>>>> It is not illegal AFAIK.

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

 MV>> Has anyone ever been convicted for changing an IMEI? If not, that
 MV>> law may be a dead letter.

 RB> Possibly, but we were talking about the law, not about convictions.

A law isn't really law until it has been "consumed" in court.

 RB>>> Ever done it?

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

 RB> With the proper interface

Nothing special, just a standard data cable.

 RB> I've read somewhere there was a drive to store the IMEI in a
 RB> non-writeable area of the EEPROM, but don't know how dar along that
 RB> is. The fact remains, simple it's not.

Simple is in the eye of the beholder. Once you know how to do it, it ius
simple.

Yes, there has been talk of storing the IMEI in another place than the flash
memory so that it would be harder to change it. Proble is that it would make it
more expensive and the competition os fierce. There is not much in it for the
manufactures. Stolen phones don't hurt them. On the contrary.

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

 RB> Thanks for the suggestion ;-)

You'r welcome. ;-)

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

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

 RB> Is that a problem when you want to make an anonymous call?

I seem to have lost track of what the objective was...


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

 RB> No, but it would be easier to buy a SIM card at a flea market in
 RB> Germany. Why go to the Netherlands for that?

If it is that easy, indeed why?


Cheers, Michiel

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