That's true. I felt the original posting implied that Hayes invented
> something entirely new; which wasn't quite true.
As far as I know, his was the first modem to use in-band signalling. It was really rather clever to build a UART into the modem and use it to let the computer control the modem over the same channel as it used to communicate with the remote system.
In-band signalling has its problems (that's what made blue boxes possible) but in this case it let people hook up modems to their PCs using a cheap generic serial interface.
R's,
John