Moving landline number to mobile carrier

You don’t do it from your ATT account. You contact the mobile carrier and tell them you want to port your landline number. They will let you know if the number can be ported. You’ll need your ATT account number and pin.

Thank you for your response sandblaster.

However, the trouble I am having is in getting a PIN from AT&T.  They provide a process for getting a PIN for porting a mobile number but there's no process for getting a PIN for porting a landline number.  Any advice?

See this topic to determine your PIN for a traditional landline.