Unlocked phone

I have been a xfinity customer for a long time. I have two I phone 14s that are paid off. I transported these two phones to a different carrier. I have been dealing with this for almost 3 weeks tickets, in person, or phone. One of the I phones is unlocked and working fine. However, my I phone will not unlock. On xfinity mobiles side it says unlock that phone reads locked. No one can give me answers.