Alternative 2 factor authentication

I set up and pay for my son’s AT&T cell phone account. I live in Panama so I dropped my own plan since it is not cost effective given I am rarely in the U.S.  So the gist of the issue is that I do not have access to the phone to be able to receive a verification code. Thus I cannot get into my account to set up a new automatic payment to replace the expired credit card in the system. Text message codes are largely being replaced by such things as authentication applications and authentication devices. Your lack of flexibility in 2nd factor authentication presents considerable difficulties to me and I doubt I am unique although I admit it may not be common. AT&T is the only bill I don’t pay through Auto Pay although I would love to be able to set it up again not to mention just be able to access my account in general. Even my cell provider here in this 3rd World Country provides alternatives to Text Message authentication!