Those rack-mount Milgo units were built like
battleships and very
well regarded in the industry. My first "high-speed" modem was a
Racal/Vadic 3451 that, IIRC, could do 2000 bps when talking to
another 3451 using RV's proprietary protocol.
Vadic had a variant 1200 baud system that wasn't compatible with 212,
too, as I recall.
De