Homephone(voip) Portpin (tello)

I'm trying to port my home phone to tello cellular and need a port pin, I found 1 definitive answer on what the port pin is-

"For anyone reading this in March 2022...

For old ATT landlines, traditionally ATT landline customer agents would ask for the 3 digits following your phone number at the top right of your landline bill to confirm your identity.

It would read "XXX XXX XXX YYY Z". 

XXX-XXX-XXX would be your phone number with area code.

So they would traditionally ask for what YYY was. 

Your landline "account number" is basically the whole thing XXX-XXX-XXX-YYY-Z

The PIN number (used for PORT requests) is basically YYY-Z (four digits).

How they came up with the PIN number was basically taking the 11th, 12th, and 13 number of your account number "YYY" + the last digit (aka 14th digit) of the account number "Z" to give you the PIN which is YYY-Z (four digits) 

Put another way, the last four digits of your "Account Number: XXXXXXXXXXYYYZ" is your PORT PIN: YYYZ

As far as I know there was no way to change this PORT PIN, manually or with online access because this was simply an account number assigned by legacy AT&T. Some of the responses above referred to a PIN process with ATT Mobile but were not applicable to ATT landline.

Hope this helps, cheers."

My billing statement only shows a 9 digit account number I'm bundled with uverse home phone internet and tv, How do I find the pin please help I've spent so many hours with customer support and looking at the forums please help