Point of sale RAS hardware?

Does anyone know of a good RAS product that supports the fast train
times needed for point of sale terminals (specifically the ability to
turn off data compression, error detection, and speed negotiation)?
Most every one I've seen is aimed at serving as-fast-as-possible dialup
network access to normal modems, but I need something that will do
1200bps (or even better yet, v.22FC) with no frills.

Can anyone suggest a product or manufacturer?


Last time I did this I cheated and bought a bunch of the old 4-to-a-card USR
Rackmount Couriers second hand and shoved a Digiboard in the back of a PC and
sent them init strings to lock them to V22 negotiation. Worked well.

Obviously this isn't an option if you want to do it on a large scale, or if
you want supportable hardware.