Cellular network problems

More information would be needed to try to diagnose the problem including a description of any fixes you might have attempted.

1) is this something new that is happening and if so is it linked to an iOS upgrade?

2) does the phone work properly in certain locations but not others/

3) are you in an area where your carrier's coverage may cause your phone to attempt to roam?

4) have you tried replacing the sim?

5) has Apple diagnosed the phone for possible hardware problems?

6) do you know of others who have the same phone and carrier as you who have no such problems?

The hard part is that there is no simple way to find the right haystack in which the needle is hidden.

If the problem does not seem to have arisen following a software update or some type of accident, it is often hard to know where best to begin.

Usually the troubleshooting is done something like this:

1) review phone settings and if everything seems fine, reset all settings. If something is incorrect, set it correctly

2) check with carrier to see if there are any cell tower or network issues that affect performance

3) check with others to see if they are having similar problems

4) do a restore via iTunes to rule out software issues

5) replace sim

6) have Apple do a hardware evaluation.

Sometimes one gets lucky and finds it early on but at times one ends up going all the way to the end before finding the problem. There are shortcuts such as, for unlocked phones, swapping in a sim from a different carrier. That can often pinpoint the problem quickly.