Due to some legislation in the US Gaijin has been unable to send SMS messages to anyone in the United States, this still has not been mentioned in the 2 step authenticator page is this indicated, and while emails can work sometimes, its hit or miss.
and for people like me who linked an email some 9 years ago it can be even worst, as i no longer have access to the primary email and have not received any form of authenticator email in several months
i have played this game since 2015, spending more money then i like to talk about on vehicles, but have a very good chance of being locked out completely from many parts of the game thanks to this broken system