Question [Q] Connection with sim

My cellphone (actually with cyanogenmod 10.1) doesn't have line, i can't send/receive sms and calls, but 3g works, i called the company but they only said to try to put the sim in another phone, it works on other phones, so what can i do? It's device's fault.. i tried to change rom, but nothing happened.
yesterday i was connected for 3-4 seconds.
what can i do?