I can not connect to 3G, as soon as I turn the cellular data and 3G phone network bars begins to disappear until it will go into research networks.
it is an iphone 4 ios 7.1.1 non jailbroken not unlocked too.
I tried to put the sim card on another iphone 3G work properly.
I also did a reset iphone but nothing.
Thank you for help please.