Port-out xFinity landline to AT&T Mobile Phone

I am having nightmares dealing with xFinity customer service. All i am trying to do is, bring the xFinity land line # to AT&T mobile phone. I was given the port our PIN as "0000". Here are few questions:

1. I have xFinity high speed cable modem, 2 Mobile lines and 1 landline, all active.
2. Is there a different account number for xFinity mobile lines than the xfinity internet or landline account #?
3. To port in the number to AT&T, I am using the xfinity high speed account #, four digit pin "0000" and the zip code but it keeps failing (when AT&T tried to port in the #)

This is the 3rd week we are trying to get the landline # ported out. AT&T even tried to conference in xFinity. Every time, xFinity/AT&T ending the call saying it's a land line, the process takes little loner, so have to wait for 24 hours. It never happens.

What am I missing, please help!!!