Well, in theory they could just tell the phone rep the unencrypted password and the phone rep could enter it into the system and the system could tell them if t

Well, in theory they could just tell the phone rep the unencrypted password and the phone rep could enter it into the system and the system could tell them if the hash matches. That's pretty much how it happens with most websites these days anyway. But I can see there's a big benefit in the rep being able to accept passwords which are obviously (to a human) the same, but would hash differently.