Anybody remember the "specially equalized line" needed for a 1200 bps terminal? 300 bps worked on an ordinary phone line (with acoustic couplers back then - dial, then when you hear the tone put the receiver into the modem cups). 1200 had a direct-connect modem, and the line was separate from the Centrex used for the rest of the place - dial the access number, then press the on-line button and hang up when the tone appeared. That line, I was told, cost as much as the Centrex service for the rest of the floor, so we used it only when doing big print jobs (DECWriter rather than Telerays).

Ah yes, the days of Ma Bell. BTW, later one we used up to 56K bps on ordinary phone lines, so I'm not sure what kind of "special equalization" was needed for 1.2K.

I guess I came along just a bit too late for that type of PBX. Everyplace I worked was either small enough that a 3-4 line phone was good enough, or big enough that they bought Centrex service from Bell.