once my iphone starts restarting by itself and didn't received any calls or messages. resetting the iphone solved the problem (not through itunes, but through iphone's settings-general- reset all) but after 10 days the problem started again and i solved by resting. but nowadays the problem is more often like 3 days once. and also the problem arises whenever i change the sim card. i'm using iphone 3gs/16gb/i os 5.0.1/not jailbreaked. my phone is also out of warranty. i'm not in my hometown and here, in this country i cant even explain my problem with phone to the people in apple store as i don't know their language. i posted in apple website to get no replies. looking for a reply, anyone please help me. I forgot to add a problem that my iphone also have difficulty with backing up with itunes. it takes so long, though at the end it fails and showes some error, forgot the number of error. I pray there'll not be any hardware problem, ll it be?