The SIM card is good. The unit has been restored through iTunes.
It was functioning last week. and still works properly in all other respects. wifi, etc.
Just can't make a call or sent/receive a SMS text. iMessage works via wifi.
Your thoughts would be much appreciated
Maybe the service is out. Has the carrier been contacted?
Yes - confirmed with the carrier that there is service and the SIM is good and activated.
Restore as new.
If the problem continues take the device to Apple for evaluation and possible replacement.
Retrieving data ...