I had to give them an IMEI for an S3 that's in the drawer to get smartphone LTE to work. What a pain in the rear. I came from an iPhone 5 though. 4 hours with customer service later, I have a working phone.
Sent from my SM-N900T using xda app-developers app
If you gave them your IMEI number, it thinks its a dumb phone and your stuck with 4G. Rep is stupid and cannot fix it, just spent 20 minutes on the phone dealing with this issue.