This document is intended to help users better understand what kind of
performance they can expect with 56k modems. It outlines what the
primary reasons for poor performance and connection problems are and
offers basic advice on what can be done to improve performance.

Why do some people have problems?

56k modem technologies (K56flex and X2) are relatively young and make
use of the telephone network in ways that it was not designed to be
used. As a result, 56k connections can only work in situations which
meet the criteria for these technologies. Because the phone networks
weren’t designed for this use, not everyone is capable of obtaining a 56k
connection. (Within this document a “56k connection” means a connection
greater than 33.6kbps using the K56flex or X2 protocol.)

In addition, because of the relative youth of the technology many
people will still encounter problems with 56k connections with only
slight imperfections in their phone line. This is due to the fact that
56k technologies are still very new. Constant improvements are being
made to the technology and in the future many of the problems that exist
now are expected to be solved. There are many versions of K56flex
firmware available to modem manufacturers. The firmware is the software
coded into the hardware on the modem, analogous to a program on a PC. As
problems are solved or improvements are made, newer versions of the
firmware are made available to modem manufacturers. Some choose to
implement them and some choose to wait.

What can be expected?

When evaluating 56k modem performance it is important to distinguish a
true problem from performance that doesn’t meet expectations. Generally
speaking, there are three types of performance being seen by the UltraNet
support staff.

The first type is a reliable 56k connection. Generally speaking, the
reliable connections fall into a speed range of 40-48k. This is the kind
of performance that is being seen at other ISPs around the country. 56k
connections do not necessarily mean 56k connects. It is a rare event for
anyone to get a connection higher than 50k and many people can not get
connections faster than 33.6. If you are getting a reliable connection
of 40-48k (or more) then you are probably getting the best performance
that you can see.

[read the review on Routers vs. Switches vs. Access Points – And More]

Some users are experiencing frequent disconnections or connections
which seem to stall or lag frequently resulting in poor throughput.
These problems may be a result of phone lines that aren’t well suited to
56k connections or they may be a result of problems with the version of
firmware that the modem is using. Users experiencing this kind of
performance should first download the latest firmware upgrade from the
modem manufacturer. If the phone line has a hiss or static on it after a
number is dialed, then Bell Atlantic repair should be able to improve the
line quality, which may help with 56k connections as well.

There are some users who have 56k capable modems who are not able to
obtain connections faster than 28.8 or 33.6 at all. In these cases the
problem is most likely related to phone service. Users should upgrade
the firmware on their modems. However if this doesn’t improve things
then it is likely that the phone line in use is simply not able to
support 56k connections. A few of the reasons for a line not being able
to support 56k connections are:

  • Distance to the Central Office
  • Multiple analog-digital conversions between the customer site and
  • Poor wiring inside the location, or within the phone network

Authentication and Combatible Protocol Errors

Some users are reporting problems with authentication or negotiating
the PPP protocols after the modems connect. It is likely that in many of
these cases the problem is not truly with authentication or negotiating a
compatible set of protocols. It is more likely that the connection
established has poor quality or problems and causes the authentication or
protocol data to be mistransmitted resulting in the errors. If you are
experiencing any of the problems above then it is likely that this is the

Things to try

Below are some suggestions to either improve your performance. Many
involve issuing AT commands to your modem. This should be done with a
terminal program, such as Hyperterminal. In cases where AT commands
should be added to the init string for a modem, this can be done by
editing the login.cmd script in Trumpet Winsock, or in Win95 do:
properties on the Dial-Up Networking connection, click the configure
button at the bottom, connection tab, advanced button, then add the AT
command to the extra settings line. Note that AT command should be
strung all together with only one “AT” at the beginning. ATE0M0 should be
used and not ATE0ATM0, for example.


  • Check with your modem manufacturer to see if there is a firmware
    upgrade available here.
  • Issue the ATI3 command to your modem. This indicates the firmware
    version of your modem. If DSP is displayed somewhere in the version
    number, you have an old, problematic firmware level. Contact your modem
    manufacturer for a replacement.
  • Issue the ATI6 command to your modem. This indicates the data pump
    version. If it includes 47BA, then you have a known bad data pump. You
    should contact your modem manufacturer for a replacement.
  • Add the ATS202=32 command to your modem init string.
  • Last, see how it works if you disable K56flex by adding the
    AT+MS=11,0,9600,33600 command to your init string.


  • If your connection gets slower and slower as you stay connected, try
    adding ATS15=128 to your init string. If you still have problems, add
    AT&K0 as well.
  • Last, see how things work if you disable X2 by adding ATS32=34 to
    your init string. Note: If you have a USR/3Com Courier X2 modem you
    need to add ATS58=1 to disable X2.


More Info

For a list of firmware upgrades and where to download them visit here.

For the UltraNet 56K Help Center follow this link.

also see this