Galaxy S problem

Hey everyone, i got a problem in my galaxy S1, it doesn't read the SIM card, the internet and all are working and working good, but when somebody calls it says my mobile is out of reach or closed, and in the mobile it doesn't show any signal, what am i supposed to do?
(already tried rebooting and restarting many times, didn't work)

Yea same problem happened to me, if you have warranty then go to the shop and tell them about the problem, i did that, and they fixed it for me and even they put Android icecream sandwich for free.