Limit yourself to one network band. To isolate the problem, try switching between LTE and 3G/4G networks. If you're having trouble making calls via LTE, try turning it off and seeing if it helps. If you're on a 3G/4G network, do the same.

*#31# is a good place to start. Setting Interrogation Succeeded, Calling Line ID Restriction Disabled' appears on the screen, and you may then call normally.