Thats a good question....Im looking in my Intuit Account and dont see where to enter a cell phone number for MFA authorization, but they DO text me the MFA code to my cell phone....but I dont know where I ever gave it to them.

Intuit knows everything about you.  They even know what you are going to have for lunch this afternoon.  Either that, or my memory is clearing and I remember providing that information somewhere along the line when logging in one time.