I bought a black berry curve and I put my 'MTN' simcard in the phone and it told me sim invalid.what do I do now.

Hi Tabbicca,

First off, who is your wireless provider? Second, you may have a defective SIM card, these can easily be replaced and shouldn't cost you anything. Your best option is take the handset to your nearest wireless provider outlet, they should be able to determine if the problem is coming from the phone or the sim.

Thanks,
Farva