Basic 2 factor authentication doesn't even cover the scope of password resets, so the idea that 2FA is flawed when used in conjunction with cellular networks is a terribly unthought out argument. If any service uses a token reset code sent to a phone as SMS or voice message, then that service is using a flawed password reset mechanism using the idea that cellular networks are highly insecure, regardless if it's also using 2FA. _Any_ single authentication mechanism over cellular networks is flawed using the same logic. 2FA, arguably, is more secure over cellular networks because it requires an authentication mechanism (the password) that is not transmitted over SMS/voice cellular in a plain format (assuming the authentication itself is sent over TLS/SSL).