Sierra Wireless AirCards

[Jeff]

Hi,

I was wondering if you could help me. I own a couple Sierra Wireless 710
aircards. They have been working fine on AT&T for a quite some time. I have
now switched my service to Tmobile. When I put the Tmobile sim card in the
aircard, the PC gives a messages "Invalid SIM". Can these aircards be
unlocked like a GSM cell phone? It has to be firmware because they sell the
same cards for all GSM providers.

Thanks,
Jeff