Quote Originally Posted by Catamer View Post
the main reason is that Authenticator has been around for a long time, they are cheap and worth every penny, if you have an iPhone there is even an app for it so you don't have to buy one. it can be tied to multiple accounts and as far as I know you can logon to multiple accounts at the same time if you used multiple email account names, if all of the accounts are under one email then I believe you have to wait 30 seconds to logon each account using a different Authenticator number. It's a small price to pay for security.
As stated earlier in this thread, you can no longer do this unless you already had it this way prior to the change.