Check that the phone is paid off
Make sure the account is in good standing
Confirm the phone has not been reported lost, stolen, or involved in fraud
Verify the phone has been active on AT&T for the required time
Find the phone’s IMEI by dialing *#06# or checking the settings
Go to the AT&T device unlock request page
Select the option for unlocking an AT&T phone
Enter the IMEI and requested account details
Submit the unlock request
Open the confirmation email from AT&T
Click the approval link in the email
Wait for AT&T to process the unlock
Insert a SIM card from another carrier
Restart the phone if needed
If the unlock fails, contact AT&T support and resubmit after fixing eligibility issues