GSM Tech
Torsten Schlabach
tschlabach at gmx.net
Sat Dec 15 11:30:18 CET 2007
Hi all!
Thanks everyone for the great pointers. I think there's lots of stuff to
digest and research.
> but FIC may not appreciate the discussion on
> their mailing list either.
Well, as Neo's don't come with a SIM lock, there's hardly a point here.
Besides that, I can see nothing wrong with trying to implement the
officialy published SIM Access Profile. And I think we need to know now
what to look for.
The question one could debate is to that extend this is a GSM technology
mailing list or not, especially if we'd go further down the road of:
> Henryk Plötz wrote:
> IIRC you'd need dual radios for [... using two SIMs at a time]
> anyways.
I understand that GSM is based on time slots. So theoretically, I should
be able to make the same radio talk to network A in one timeslot and
network B in another. But that might be too simplicistic for whatever
reasons. Also there is still the use case that I had two SIMs (just with
different numbers and maybe different accounts == phone bills) but still
on the same phyiscal GSM network. At least that should be doable with
one radio, shouldn't it?
Well, I think this is getting OT for this list, isn't it?
Regards,
Torsten
Steve schrieb:
> Joe Pfeiffer wrote:
>
>>(just a couple of additional comments to what Steve says)
>>Steve writes:
>>
>>>The GSM Modem as a black box:
>>>
>>>>From my understanding of the NEO 1973, the GSM modem is roughly
>>>analogous to a computer modem from the past. (Not the cheap "winmodems"
>>>that are so abundant these days.) It is connected via a serial
>>>connection to the portion that runs open software and communicates over
>>>the GSM network. TI has provided a set of "AT" commands to preform a
>>>limited subset of the functionality that the modem is capable of. If
>>>you want to use more advanced or unintended functionality, you'll have
>>>to figure out how to do that on your own.
>>
>>The AT commands are actually part of the GSM standard (I don't know if
>>TI has agumented, nor if they've implemented all of them). My
>>understanding is that getting any additional functionality out of it
>>starts with prying the cover off the chip and goes downhill from
>>there :)
>
>
> I'd agree with the statement about the AT commands, but I do think its
> probably possible to get unintended functionality out of the GSM modem
> without resorting to decapping the chip. After all that is exactly what
> the unlockers are doing.
>
> The unlockers are probably a major reason why TI is so paranoid about
> the workings of their chipset since that is where the SIM and provider
> locks are usually implemented. I wish I could give you more information
> about the techniques they use, but I don't know what they are. It would
> be interesting to find out, but FIC may not appreciate the discussion on
> their mailing list either.
>
> -Steve
More information about the device-owners
mailing list