All codes are lost if you change phones

An application for two-factor authentication must be 100% reliable. This simply isnt because if you change phones, all your access codes are lost. In my case, this locked me out of a 6 digit Coinbase account. Coinbase is so backed up with customer service on this issue it took over two weeks for them to recover my account.

Telebyte about Google Authenticator, v3.0.0