Put your phone into airplane mode, remove your SIM card, turn phone off, wait for a few minutes...put the Sim card back in, turn the phone on, turn off airplane mode and let the SIM re-activate. If this doesn't fix the problem, have your carrier reset your line and then try the above steps again. Should be good to go! :-) Just followed those same steps with carrier reset on a customer's iPhone 6+ and it worked perfect.