V.90 Known Issues
With BayDSP V.90 Modems
The BayDSP V.90 digital modem technology has been
extensively tested with all popular V.90, X2, K56flex, and V.34 client
modems. The V.90 implementation is subject to some interpretation
differences during the coding process by the variety of organizations that
are releasing products for the client modem user.
Consequently, incompatibilities exist between the
central site V.90 modem releases and certain client modem implementations,
V.FC (Fast Class) modems are not supported by BayDSP
V.32terbo operation (a 19.2Kb/s modem of operation similar
to V.FC) may operate with some modems but is not supported in this release.
The version of BayDSP Digital Modem code included in
this release supports speeds from 2400 (V.22bis) up through 33.6 Kb/s (V.34
with extended rates) up to V.90 56Kb/s.
The following modems are known to exhibit connectin
reliability problems with the BayDSP Digital Modems:
Ongoing client modem flash upgrades resolve many of
these issues; however, the following chipsets/client modems have been found
to exhibit limited compatibility with the BayDSP V.90 modem implementation.
AT&T Paradyne Comsphere 3810
AT&T Paradyne 3740-A1-201
Motorola Codex 3261
Racal V.34 models 3292 and 3264
ESS x2 Chipset
The ESS x2 chipset previously had a bug that affected
transmission and detection of the x2 signature with the handshake.
Consequently, connections with the BayDSP modem would fall back to V.34
modem. ESS has since fixed the x2 signature requirements; however,
not all manufacturers that use the ESS chipset have incorportated these
changes in their client modem releases. One client modem in this
category is the Netcom ESS56K.
Cirrus Logic Chipset
The Cirrus Logic chipset previously had a bug affecting
x2 training sequence timings. Consequently, connections with the
BayDSP modem would fall back to the V.34 modem. Cirrus Logic has
since fixed this problem; however, not all manufacturers that use the Cirrus
Logic chipset may have incorporated these changes in their client modem
relesases. Client modem manufacturers who use the Cirrus Logic chipset
in some of their modems models are Digicom, GVC, Atlas and Zoltrix.
Racal ALM 3239
The Racal ALM 3239 modem does not connect with the BayDSP
modem. During the handshake sequence, INFO sequences are incompatible
between the 3239 and the BayDSP digital modem. Consequently, the
handshake sequence does not progress to data modem and the modems disconnect
It is very important that the client modem user check
the client modem manufacturer's Web site for any upgrades that may be available.
A good site for links to client modem manufacturers is http://modems.rosenet.net/
. or check out ECSIS.NET
Modem Information Pages .