 They would start with standards supporting high speeds and progressively fall back to slower standards until there was a response.Thus, two USR modems would be able to connect at 9,600 bit/s, but, when a user with a 2,400 bit/s modem called in, the USR would fall back to the common 2,400 bit/s speed.This would also happen if a V.32 modem and a HST modem were connected.