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
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?

We use the Cisco AS5400 in which you can enable/disable any option as
you see fit using resource pooling.

We use it to support KFLEX modems which fail to connect properly w/ the
v.92 tones. The way it deterimes which settings to use is based on
called station id.

We also find modems that try to to retain to highest speed tend to
reach the limit and drop the connection. Most of our customers are in
rural areas w/ poor quality phone lines.
We found it was easier to create resource groups to lock people to
21000 baud via setting their connection number than giving the customer
init strings to limit the connection that way. Sure there are probably
better solutions, but this has solved nearly all connection problems
we've seen.

I realize you may end up not using cisco, but I'll include a small
example just in case it's useful to anyone.

IOS (tm) 5400 Software (C5400-IS-M), Version 12.3(1a), RELEASE SOFTWARE

resource-pool enable
resource-pool group resource MICA-modems
range port 1/0 1/107
range port 2/0 2/107
range port 3/0 3/107
range port 4/0 4/107
range port 5/0 5/107
range port 6/0 6/107
resource-pool profile customer any
limit base-size all
limit overflow-size all
resource isdn-ports digital
resource MICA-modems speech service any
dnis group default
resource-pool profile customer v90
limit base-size all
limit overflow-size all
resource MICA-modems speech service v90
dnis group v90
resource-pool profile customer k56flex
limit base-size all
limit overflow-size all
resource MICA-modems speech service k56flex
dnis group k56flex
resource-pool profile customer v34-28800
limit base-size all
limit overflow-size all
resource MICA-modems speech service v34-28800
dnis group v34-28800
resource-pool profile service v90
modem min-speed any max-speed 56000 modulation v90
resource-pool profile service k56flex
modem min-speed any max-speed any modulation k56flex
resource-pool profile service v34-28800
modem min-speed any max-speed 28800 modulation v34
resource-pool profile service any
dialer dnis group v90
number 2533219668
number 3605459668
dialer dnis group k56flex
number 3605429667
number 3605459667