One of the most difficult questions to answer quickly is: "Why do I sometimes
get disconnected when I am on line?" A dropped connection can occur for
a variety of reasons.
A common cause of disconnects is line noise. As a test, try unplugging
EVERYTHING connected to your phone lines: caller ID boxes, extension telephones,
cordless telephones, other modems, fax machines. Also unplug your laser
printer from the AC wall outlet. We have learned that many telephone line
'surge protectors' or 'noise filters' will seriously impair your phone
line. Also avoid any type of "splitter" on your line. Test your connection
with the modem being the ONLY thing connected to your phone lines. If the
problem goes away... then you have something in your house causing you
to disconnect. Do not route the phone line within three inches of any electrical
cord or extension cord, or PC CPU cable, Printer cable, Monitor cable,
any electrical appliance or power supply. Especially avoid laser printers,
cordless telephones and uninterruptable power supplies (UPS's). Inductance
from electrical lines and radio transmitters can wreak havoc with phone
If the line noise is not being induced inside your house it may be induced
in the cable somewhere between your house and your local telephone exchange
central office. Your line may have a one or more of conditions the telco
calls 'bridge', 'ground loop', 'cross talk', or 'bad loading coil'. Any
of these conditions will cause random noise and unpredictable disconnects.
For noisy lines, try increasing a setting that tells the modem how long
to wait (in tenths of a second) before hanging up when it loses carrier
detect. This guard time allows the modem to distinguish between a line
hit, or other disturbance that momentarily breaks the connection, from
a true disconnect by the remote modem. See below:
|Technical Tip: Modem connections are usually dropped because
the modem either 1) lost the DTR (Data Terminal Ready) signal or 2) lost
the CD (Carrier Detect) signal. If the above suggestions do not resolve
the problem, You can modify the length of time the modem will wait before
concluding loss of DTR or loss of carrier by modifying the S10 and S25
To set the S registers, go to Start | Settings | Control Panel | Modems.
the Properties button for your modem. Click the Connection Tab, then the
Advanced button. In the Extra Settings box, add S10=100S25=200
S10 Sets the duration, in tenths of a second, that the modem waits
to hang up after loss of Carrier Detect (CD). This guard time allows the
modem to distinguish between a line disturbance from a true disconnect
(hang up) by the remote modem. The default setting is usually around 14.
A generous setting of 100 should significantly reduce connection breaks.
S25 Sets the duration, in hundredths of a second, that Data Terminal
Ready (DTR) must be dropped so that the modem doesn't interpret a random
glitch as a DTR loss. The default setting is usually around 20. A generous
setting of 200 may reduce connection breaks.
If the above seems to help, contact your phone company and request the
line be checked for noise at the network demarcation block at your house.
Do not let them just check the line from the central office end, ask to
meet the repairman at your house and get him to report the results of his
tests to you. If you encounter resistance from them because you have a
modem, call back and tell them your fax machine is not working well with
your phone line.
Sometimes defective cables and loose connections will cause disconnects.
For external modems, if the serial cable is old, adapter pins bent, or
cable cracked, replace it or try another one. Make sure your serial connections
are TIGHT. Examine your telephone cable between the wall jack and the modem,
or better still try replacing it. If portions of the telephone cable between
the network interface and your wall jack have been stapled to the wall,
examine the cable carefully. If possible try another jack, or the jack
on the telco network interface itself.
If you have call waiting, remember to add a *70 (or other code,
depending on your phone company), to the front of the phone number to disable
call waiting. Otherwise every time someone calls you, the modem may disconnect.
This can also be specified under Dialing Properties in the Modem
We have a 30 minute idle timer, which means if you leave your computer
logged in, but do nothing which exchanges data over the link, then your
call will be disconnected after 30 minutes of idle time. An example might
be when you are reading or answering your email. Even though you may be
typing a reply, all activity is taking place on your computer, so this
will not cause any data to be transmitted. After 30 minutes the call
will be disconnected. Windows 95 / 98 has a 20 minute time-out setting,
but this should warn you before it actually disconnects. You can adjust
the setting in the Internet Options Control Panel. Look under the
Connection Tab and Settings.
Although rare, your modem may be set up to automatically disconnect
after a certain period of inactivity. Go to the Modems Control Panel, click
Properties for your modem, then the Connection tab. Uncheck the idle time-out
Generally, you should hold a connection for as long as you wish....
there will ALWAYS be an occasional disconnect, we are after all, dealing
with phone lines pushed to the very limits of their capacity when using
the latest generation of modems. But you should not get repeated disconnects,
if you do something is wrong and you should methodically follow the steps