Problem updating iphone 3g to 4 2
Some i Phone users have discovered cellular data issues after installing the i OS 12.1.3 update, showing “No service”, no cellular data, no cellular reception bars, and sometimes seeing a “Cellular Update Failed” message similar to what was happening with some i Phones after installing i OS 12.1.2.
This seems to mostly impact i Phones on particular cellular networks, but it’s not entirely clear why some i Phone devices will experience cellular data problems after installing the i OS 12.1.3 update while others don’t.
You can also try resetting network settings in i OS.
A downside to this approach is that you will lose all saved wi-fi passwords, any custom DNS entries, or other network specific settings customizations.
If this works, great, though it’s not entirely clear why it would.