i hav this problem and i hate it. as i accidentally upgrade my iphone using itunes and now my network carrier "My Maxis" always can't detect my network..sometime when i'm not in maxis coverage "my maxis" change to "No network" the whole day until i change my sim card to other hp and put it back to iphone and the problem solve..I don't know how to fix it..now i'm carrying extra hp incase for emergency..can somebody solve this problem..PLEASE>