The OS that you're using shouldn't cause this trouble. You should contact your phone carrier. If this won't help you, you should try to reset your phone without having the trouble of data loss:
- Hold down the home/sleep button together until you see the apple logo and then release, then wait for the phone to boot back up.
. Or you can reset the network setting from the smartphone's settings:
- settings > general > reset > reset network setting
If this won't help you, you can try to contact Apple support.