New phone line with Xfinity

They were porting my number in from At&T. On phone for over an hour. 3-way call with AT&T and your rep. AT&T unlocked phone and we setup the pin numbers. Your rep gave me a temp number and said it would be a few minutes, and it would port over. After restart and it will be fine. Phone now has no service and says "invalid sim card".   Network locked sim card.  Never can get someone to talk to me.