Switching my phone to a new account

You need to process a transfer of billing responsibility of your line to you. When you accept the transfer, you will set up your own account and plan. More info here: https://www.att.com/acctmgmt/tobr/

New account as in new phone number?   Or move your old number to a different account owner? 

Have you plans to close down the old one? 

Needs clarification 

Old number to new account. I’m trying to pay for my own phone but it’s on my mom’s account and I’m not sure how to transfer or get a new plan for my current phone.