[Asterisk-Users] "GSM cards" / "mobile phone cards" for Asterisk?

[Tomasz Chmielewski]

I was wondering if there is something like that on this Earth:

Some of our users are "mobile users" - they are rarely in one place for 
longer than 15 minutes.
They use mobile phones a lot.

 From our mobile operator we have an offer which allows us to call for 
free between our mobile phones.

So the idea is to put a SIM card inside the Asterisk box, equipped with 
a special card, a card which would be a mobile phone really.

This would allow all office users to reach our mobile users without the 
need of buying additional phones for the office users.
Office users would call Asterisk over IAX, and asterisk would call 
"mobile users" using a free GSM/mobile.

Does anyone have an idea if such cards exist, and if so, if they work 
with Asterisk?


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Tomek
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