Acoustic Couplers pretty much topped out at 300 bits per second. The
Don't tell Racal-Vadic about that!
They had a 1200-bps ACOUSTIC-COUPLED modem on the market in the 70's. Anderson-Jacobsen even licensed it, and made similiar units under their own label.
No, it was *not* "bell-212" compatible. It used the propietary Vadic
3400 tones/encoding scheme.Worked *way* better than Bell 212, which suffered from the fact that the Tx and Rx frequencies were exactly one octave apart. $DIETY only knows what Bell labs was thinking when they did _that_.