Features - US Robotics Courier V.Everything 3CP3453 Getting Started Manual

Features

33.6 Kbps Connectivity
The Courier contains software that enables 31.2 and 33.6 Kbps
connection rates, as well as improves throughput at lower
speeds. While line conditions may not always allow for
33.6 Kbps connections, the new software makes it more likely
that your Courier will achieve and maintain 28.8 Kbps
connections. It can add up to 4800 bps to the average V.34
connection rate.
Selective Reject
Selective Reject is an optional part of the ITU V.42 (LAPM)
specification. This feature improves performance on noisy lines
by reducing the amount of overhead incurred when the protocol
must resend data due to errors.
When selective reject is active, only the frame that contained the
error is resent, instead of the frame plus all of the following
unacknowledged frames. You can disable selective reject by
changing a setting in S-Register 51 (see Appendix A, Alphabetic
Command Summary, in the Courier Modems Command
Reference manual).
Attaining Speeds Above 28.8 Kbps
V.34 connections at 21.6, 24.0, and 26.4 Kbps are common. To
get connections of 28.8, 31.2, and 33.6 Kbps, line quality must be
pristine end-to-end. In addition, 31.2 and 33.6 Kbps connection
rates are possible only when the device to which you are
connecting also runs software that supports speeds above
28.8 Kbps.
If you are curious about the role that line quality plays in
attaining and maintaining high-speed connections, and want to
learn what you can do to improve connections, request the
following document from our Fax on Demand service: Phone
Line Quality and High Speed Connections. The Fax on Demand
number is (800) 762-6163.
1-4 Courier V.Everything Internal Modems: Getting Started