So this would be a question about a situation that I have been involved with before and any attempt at finding a reasonable solution that would help resolve this dilemma has been quite difficult to find. And so, I will paint a portrait of the scenario: So hypothetically, let's assume that <User> has Two-step Authentication activated on Mozilla Firefox and is on a weekend excursion of the Mighty Mississippi River and so happens to lose that phone to the surging undercurrents and a tumultuous exodus to those murky depths, but On Top of This Person's Game, quickly attains a new phone (yet in a moment of rushed deliberation and penchant to make some minor miscalculations (to spice things up, of course) couldn't keep the old phone number. And so, in the course of updating the newer phone version and the number on numerous sites and has arrived at finally updating Mozilla Firefox account, which asks to Two-step Authenticate by sending the code to the bottom of the Mississippi River (or some bull shark's belly (who is most likely very confused about why his lunch is buzzing and starts to be concerned about his own gut health issues). And so, the Issue at hand is, how does one get thru the Two-step process, which only seems extremely eclectic about sending codes to that ex-phone instead of paying attention to this newer, younger phone version. Thanks in advance, - Lost in a River