When switching carriers, you'll need your Mint account number and porting PIN. Here's exactly where to find both pieces of information.
Open the Mint Mobile app → Settings → Account Info.
Your account number is listed at the top.
Or log into mintmobile.com/login.
Text PIN to 670 from your Mint number.
You'll get a 6-digit PIN valid for 24 hours.
If you wait more than 24 hours to start the port, request a fresh PIN before retrying.