My daughter has the Impact and has had it for about one month. This morning, the phone asked for the sim card, but it is already installed. The SIM is several years old, it is Cingular Branded, formerly in a Firefly a Razor and a Xenon. 

Could the sim just suddenly fail/go bad?  Im pretty sure the phone has been dropped a few times, but it was fully functional yesterday.  I had a sim card from an old AT&T Blue plan for probably 7 years, but that may not mean anything at all.

If the sim is indeed bad, what is the procedure for obtaining a new one and will AT&T hose me with some ridiculous fees?

For a 13 yr old, this is of almost national security importance, so any advice will help me resolve this quickly.

Thanks in advance for help.