how can i stop the thief from using my iPhone? My i phone 5 was stolen and i'm freaking out because the thieves keep on using my i phone. i knew this because when i contacted my i phone it answered me. 

i tried to locate it but it keep on showing offline then i remotely erase my phone but it seems that the thief is not connecting to the internet. i'm afraid because he has the freedom to access my contacts and pictures! please help me.
I believe in some country you can file a complain with your IMEI number and UDID (which you can have on your purchase proof or in iTunes in last device) and the police can then ask Apple to block the phone.

Anyway, the best practice here is to file the complain, you never know what happen with your data...

BTW, no need for internet connection because it's directly over GSM network