Here's a rundown of the most common solutions for unwanted disconnects
Disable call waiting
You probably know this already, but you should disable call waiting. The
"click" of an incoming call may disconnect you, though newer modems have
improved error correction that is less sensitive to this.
In most areas, you can disable call waiting on a touchtone line by placing
*70, in front of the phone number, like so:
*70,555-5555
If your lines do not have touchtone service, and instead use pulse dialing,
the command is 1170,.
Note that in some areas, the phone company charges you each time you disable
call waiting. Also, some areas use different commands, or may require you to
request the ability to disable call waiting. If in doubt, call your phone
company.
Upgrade firmware, init strings, and drivers
Many disconnect problems can be solved by loading a more recent version of
the firmware. Check the firmware page.
Likewise, having the correct modem init string or driver installed is
important. Check the inits and drivers page.
Try unplugging any devices from the back of the modem
Modems have two phone jacks on the back: one is for the line connected to the
wall jack. The other is for plugging in a telephone, answering machine, fax
machine, etc.
Try unplugging your telephone or any other device attached to the back of the
modem. Some devices may cause problems. For instance, some telephones draw power
from the phone line every 15 minutes to power the circuits that keep track of
speed dial numbers.
Try unplugging other telephone equipment in the house
It's possible to have too many devices on your phone lines or extension. Try
unplugging extra phones, fax machines, and answering machines to see if the
disconnects stop.
Try lowering the port speed
Older PCs may have weak UARTs that are not capable of high speed
communications. As a result, you may get frequent dropped connections and/or
poor modem performance due to resent packets.
To test this, try lowering your port speed to 38400 or even 19200. If the
dropped connections cease, a slow UART may be the problem. A replacement serial
port card should fix the problem.
For use with a 56K modem, you want at least 16550 UART. Internal 56K modems
should include a 16550 or higher UART on the card.
Lowering connect speed with K56flex or K56flex/V.90 modems
Some K56flex owners have found that they can reduce disconnects by setting a
limit on the initial connect speed. The commands for controlling maximum connect
speed are different for Rockwell-based and Lucent-based K56flex modems.
On most Rockwell-based K56flex modems
If you normally get disconnected when you connect at 48000, you might try
using:
+MS=56,0,9600,46000
If that didn't work, you would try:
+MS=56,0,9600,44000
+MS=56,0,9600,42000
and so on, reducing the maximum connect speed by 2000 each time. Experiment
with different numbers to see if lower numbers result in fewer disconnects.
On most Rockwell-based V.90 or V.90/K56flex modems
If the modem supports V.90, use the +MS=12 command (see above for
instructions):
+MS=12,0,9600,46000
On Lucent-based K56flex modems
The S38 command can be used to control the maximum connect speed. The values
between 2 and 14 set the maximum speed between 32K and 56K. So, if you normally
get disconnected when you connect at 48000, you would try:
S38=9
to set the maximum connect speed to 46000. If you still get disconnected, you
might try:
S38=8 (for 44000)
S38=7 (for 42000) and so on.
USR Sportsters get slower and slower, and may disconnect suddenly
This is the x2 version of Spiral Death Syndrome. The fix in most cases is to
add S15=128 to the init string to disable V.42 hardware error correction. It may
also be necessary to add &K0 to the init string to disable V.42b is hardware
data compression, though this should be a last resort, as performance will
suffer when downloading non-compressed files.
Lucent LT Win Modem disconnects
1. Try using the init string AT&FX. (See the next step for instructions.)
2. Set Windows 95/98 Dial-Up Networking to use software flow control. Here's
how:
1. Doubleclick My Computer, then doubleclick the Dial-Up Networking folder.
2. Right-click on your connection icon and choose Properties.
3. Click the Configure button.
4. Click the Connection tab.
5. Click the Advanced button.
6. Put a check next to "Use flow control" and select "Software (XON/XOFF)."
7. In "Extra settings," enter "AT&FX".
8. Click OK to save changes.
3. If that doesn't help, you might try lowering your connect speed to 57600.
(The speed setting is on the first screen when you get Properties on your
connection icon.) This should be a last resort, as it will affect your download
speed somewhat.
Macintosh issues
The Macintosh uses an 8-pin serial port, rather than the 9- or 25-pin port on
most other computers. As a result, Mac modem cables handle DTR differently, and
DTR is often used as a disconnect signal.
The classic symptom of unwanted DTR disconnect on the Mac is getting knocked
offline when receiving a large stream of data. This may happen during a
download, or when issuing a dir command in a command-line FTP
program.
To disable DTR hangup, add &D0 (zero) to the end of your init string.
