Why wont my sim card work?

i have a blackberry 8520 on an orange contract. the phone is unlocked though so it can accept any sim card. My friend took my sim out and because the sims are pretty hard to get out of the blackberrys, it broke. i have ordered a new sim which will come within 4 days. however i need my phone for the next 4 days so i went and bought a pay and go orange sim with �5 credit. when i put it in my phone it says 'sim card not provisioned 2' and wont work. what does this mean? i have had my friends pay and go sims in my fone before and they have worked fine.