Q. Why does my modem abruptly disconnect sometimes?
Generally, there will always be an occasional disconnect. After all, we
are dealing with phone lines being pushed to their limits with V.32 and
V.34 modems. Phone lines were designed for voice, not for data transmission.
But if you're getting a lot more than the occasional disconnect, something
is wrong and you should methodically follow the steps below.
Reason & Solution #1:
Disconnections may be caused by momentary drops of DTR (Data Terminal
Ready). By default, most modems respond to a drop of DTR by hanging up.
With US Robotics and other modems, add S25=200 to your Modem String. This
sets the duration, in hundredths of a second, that DTR must be dropped
so that the modem doesn't interpret a random glitch as a DTR loss.
Reason & Solution #2:
A similar possibility to the one above is that your modem could not distinguish
between a line hit, or other disturbances that momentarily break the connection,
from a true disconnect by the remote modem. Add S10=100 to the Modem String
to set the duration, in tenths of a second, that the modem waits after
loss of carrier before hanging up.
Reason & Solution #3:
If you have call waiting and a call comes in while you are connected to
your ISP, your modem might interpret the second signal as a disconnect
by the remote modem. Ask your phone company how to temporarily disable
call waiting. Also, keep in mind that ISP has an idle timeout.
Reason & Solution #4:
If you suspect line noise, try solutions #1 and #2 above. Also, listen
in on the line for static, ask your phone company to test the line (although
they usually only test for voice grade as opposed to data grade), and
try reducing your baud rate (a.k.a. port speed). Also disconnect EVERYTHING
from your phone lines, including a laser printer from the electrical outlet.
Do not use devices that allow you to connect your phone line to an electrical
outlet. Also, keep the phone line at least three inches away from electrical
cords, extension cords, printer cables, etc. Inductance from electrical
lines and radio transmitters wreaks havoc with phone lines. And avoid
using phone splitters of any kind.
Reason & Solution #5:
One common cause of disconnects is modem incompatibility between your
modem and the remote modem. No modem is completely compatible with every
other modem. Be sure to check with the modem manufacturer periodically
for firmware and driver upgrades. Do not assume that just because
your modem is new that it contains the latest firmware and drivers.
Reason & Solution #6:
Check your phone cable for defects. Or better yet, just replace it with
a brand new one. Also, if you have an external modem, make sure your modem
cable connections are tight and the cable is also free of defects. Generally,
the modem cable should be replaced every year or so, depending of course
on frequency of use.
Reason & Solution #7:
If you're disconnected shortly after logging in try to add a Modem String
to make your connection stronger. Check your modem's instruction manual
for specific information about settings.
To add this int string to your modem in windows you need to:
Open My Computer
Open Control Panel
Open Modems
Properties
Connection
Advanced
Under extra settings add the following command: S10=100S25=200
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