bell, vadic, 212s, acoustic couplers

[utzoo!decvax!ucbvax!unix-wizards]

>From csk at UCLA-Security Thu Oct 15 22:42:55 1981
There is no such thing as a 212 acoustic coupler!

Vadic invented the 1200 baud encoding system used today.  However, when
bell chose the 212, it chose a set of encoding frequencies (purposely)
which have resonance problems which make it impossible to build
acoustic couplers for the 212.  Vadic remained with its own standard
which DOES allow acoustic couplers.  It is generally felt in the
industry that the Vadic standard is superior to the Bell 212 standard.

At the computer end, buy Vadic triple threats and no one will be unhappy.
At the user end, use whatever is convenient.  I use a Vadic 3434 (acoustic
coupled) and it works just great.  However, expect problems with hotel
and other places because of noisly lines, phones that don't fit, etc.

--charley kline