Can't unlock Iphone 13

Let’s be clear on this.  You bought a new phone 13 from AT&T in the U.S. (or an authorized retailer like Apple, Best Buy, etc.) and use the phone on the AT&T US network for a couple of years.  Is all if that correct?  Was the phone bought a full price at time of purchase, on on an installment plan?

I bought it in an installment plan but already payed every thing(that's why it said need to be on AT network for 60 days and not ya didn't fully pay your installment for this phone). But i changed to another service provider for quite a long time now.

I bought it in an installment plan but already done paying every thing(that's why it said need to be on AT network for 60 days and not ya didn't fully pay your installment for this phone). But i changed to another service provider for quite a long time now.

If you changed to another service provider a “long time ago”, then what’s the issue?  If the phone was still locked to AT&T, it wouldn’t have been working with the other provider this entire “long time”.  Unless you were using it on an AT&T MNVO.

This is the requirement for unlocking a phone that was paid off early.

• Paid off early: The wireless number assigned to the device must be active for at least 60 days. Wait 48 hours after you make your final payment to submit your unlock request.

Did you meet this requirement with the phone in question?