No phone connection on Galaxy Core prime after factory reset.

[AC Question]

My Galaxy SM-S820L problem started with a Kernel Panic Upload error. A cache wipe and factory wipe and reset finally relieved that issue and the phone seemed to be acting as normal with all apps working until I tried to make a phone call. The phone is stuck in Roaming and I get a "your phone is not authorized to make this call" message. Several calls to Straight Talk didn't help. They want to change phone number and set up a new plan from what I can understand through the language barrier. Any ideas? Bad SIM card?