Internet connectivity

Hi, i am an iphone 5 user. Currently my IOS version is 6.0.2

Here's the problem, the phone indicate that i have 3 bar or signal strenth for 3g but i can't connect to the internet. Safari mentioned as No internet connection available.

I switch the airplane mode ON and OFF so that it will search the network again. This time the phone shows GPRS/1xRTT connectivity which i still can't connect to the internet. Then i turn OFF the phone but with the same result.

I later reset all network setting which manage to solve the problem temporary because it always happen again.

I don't think this problem come from the carrier provider since my office mate don't have this problem with their phone (other phone maker).

I think the is something not right with the phone. I notice this start from Iphone 4 and 4S and now 5.