Hi @notbob ,
Are you using the 'phone' app to make calls or a 3rd party app?
If using the normal phone app, try starting the phone in ''safe mode'' and check if it works OK.
If it does work OK then a downloaded app is the cause of the problem. The trick is to find out which one.
If it still doesn't work try a factory restore, (also known as a hard reset), using the phone's factory restore feature.
Before you perform a factory restore, backup the phone first.
Be aware that a factory restore will erase all your data and downloaded apps. It will be restored to its' factory default condition. That's why it's important to do a backup first.
Once the factory restore has been completed, check if the phone works correctly. If it does then restore the phone, using the backup that you made earlier, using the phone's restore feature.
Once the restore has been completed, check the phone again to see if it is still OK.
if it is then the restore (reset) has fixed the problem.