The person who made that video didn’t have a Courrier Dual Standard on each end of the connection - US Robotics’ V.FC handshaking was very fast, it didn’t do that bouncing around.
That, and OMG, insert a S11=50 and a X6 in the initialization string to speed things up! When your local Pyroto Mountain is at war, you need to be ram-dialing that number as fast as possible (less so if ST:TNG was on).
