September 2000--A common question
in the message boards is why Internet connections disconnect all the
time. Our crystal ball tends toward cloudy and itís hard to tell for
sure from where we sit, but after doing some testing with a
Rockwell/Conexant WinModem, some ideas surfaced.
Before we get to the details, a little history lesson is in order.
What is a modem? Itís a device that converts computer information to
sound, so it can travel over a phone line, and then converts the
sound back into computer information at the other end. This process
is called modulation/demodulation and the term got shortened to
something easier to pronounce: modem.
Originally, modems were hardware-based, with chips
on the modem doing all the work. Around the time that 14.4 modems
became popular, Rockwell (one company that makes the chips that
modems use, now called Conexant) found a way to reduce the overall
cost of building a modem by removing one of the hardware components
and substituting a program running on the host computer to do the
same thing. These modems were referred to as ďRPI" modems, and
caused grief for some users, especially with slower computers
because the host computer could not keep up with the process
resulting in data loss or dropped connections.
As modems got faster, RPI went by the wayside and
we thought we had seen the last of that situation. Unfortunately,
that was not to be the case. As host computers got faster,
manufacturers started to look at more ways of trimming costs and
went back to having the computer do some of the work.
Hardware vs. software
The modem process can be divided into three stages: the controller,
which handles all the controlling activities; the data pump, which
is responsible for the modulation/demodulation function; and a data
access arrangement, which is the part that connects to the telephone
If a modem has all three parts on the card or in
the case itís considered a hardware-based modem. Internal
hardware-based modems are a rare breed today because of the higher
costs involved. Usually, a driver that runs on the host computer,
leaving just the telephone connection on the interface card replaces
both the controller and the data pump. This is why WinModems can be
sold for $20 or less; the major chips that perform those functions
have been removed.
So what seems to be the problem with all of this?
It appears that the functions that the modem hardware used to do
have not been duplicated exactly, resulting in subtle differences.
These differences may be causing the connection difficulties some
people are experiencing.
My phone line canít handle a 56K connection. I
have checked and rechecked the lines and itís just not going to
happen. I verified this using the 3Com line test. More information
about this valuable test is available at the 3Com
and is worth checking out.
I installed a Rockwell/Conexant WinModem to test
some things for a client, and I found that the modem was defaulting
to using a V.90 (i.e. 56K connection) even though the phone line
canít handle it. When using a hardware-based modem, the handshake
sequence, all that hissing and squealing you hear when the modem
connects, showed v.90 was a problem and the modem switched down to
V.34, which has a maximum speed of 33.6K. This is the fastest speed
non-56K modems can handle.
The Rockwell/Conexant WinModem I was using did not
detect that V.90. It would not work during the handshake sequence
and went ahead and tried to use it anyway. This resulted in many
problems with all connections dialed. I tried a variety of remote
systems and in each case, the result was the same: connection
I used the proper command to tell the WinModem to
default to using V.34 instead and in all cases; I was able to
establish a clean connection each and every time I tried. I could
not get the connection to fail.
What does this mean? Iím not sure, but I suspect
Iím not the only one with a less than pristine phone line and this
may be the reason for some dropped connections. If you have a
Rockwell/Conexant-based WinModem, making these changes may be
worthwhile. The connection will be slower, since 33.6 is the maximum
allowed, but it may turn out to be more reliable, which will be
1. Perform the
test. If you need a terminal program installed, I recommend
HyperTerminal, a free program available
2. If the line test shows your line canít handle
56K, open up Control Panel | Modems | Diagnostics | point to your
modem | More info. See if Rockwell or Conexant is listed in the
information that is displayed.
3. If Rockwell or Conexant is listed, try this
change: Control Panel | Modems | point to your modem | Properties |
Connection | Advanced. In the box marked ďExtra Settings", type
this, exactly as it appears: +ms=v34,1,75,33600,75,33600, then click
OK. Go online and see if your connection is more reliable.
We'll be testing other WinModem chipsets and weíll
get to the results in another article.
Until next month, stay connected!