GSM Tech

Thilo Bangert bangert at
Sat Dec 15 14:39:09 CET 2007

>  > 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?

it seems to me you make a fair share of assumptions on behalf of the GSM 
network which are most likely not valid. GSM is split into multiple 
channels, some of which are used for signalling. i _think_ it is 
impossible to be available on the channel posing as two devices at the 
same time using only one radio. but then again if the allowed idle time 
on the signalling channel is large enough for the phone to be able to 
switch among the multiple frequency bands.... that would mean it is 
actually simpler to get it to work with two different networks...

..but thats only wild speculation.

You really should checkout the GSM specifications for that type of 
information - appears to carry many of these.

last but not least, non of this is feasible through the highlevel 
AT-command interface of the TI chip on the Neo.

> Well, I think this is getting OT for this list, isn't it?

you bet - but then, what would be more appropriate?

> Regards,
> Torsten

best of luck

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