Blackberry 8820 - SIM not allowed HELP

[Challehx]

I'm using a blackberry 8820 and my simcard has been working fine as it should, but this morning i looked at my phone and it read at the top where the network carrier usually has it's name and it said "SIM not allowed" and the phones signal was "SOS" in red.
My Friends simcards work in my blackberry fine without the "SIM not allowed" message.
I tested my simcard in my mothers phone and it worked fine on her motorola.
But it just shows as "SIM not allowed" i've also tried connecting to a network manually but no luck.
Is there a Solution?

[ndub33]

Make sure that you are mounting your SIm correctly in your device. If that doesn't correct your issue, give your carrier a call, they may have some insight on their end.

[Dubdub]

Might need a new SIM card too. Heard of that happening more than once.

[Challehx]

Might need a new SIM card too. Heard of that happening more than once.

my sim card works on every other phone. just not the blackberry all of a sudden..

[thump1]

If you are on AT&T, go to their website and you can unloack the sim card without haveing to contact them voice. There is a condition from time to time that will cause this with AT&T. I have done this on a few occastions. It's free also. That is if you sim card is not fried for some reason.