Problems dialing out
The most useful tool for diagnosing dial-out problems
is the -x9 option to
This option causes cu to display
diagnostic output when attempting to dial out. To get a
debugging output, enter the command:
cu -x9 phone_number
is the phone number of the system you wish to dial.
You may experience one of the following problems on dialing out:
Modem dials, but does not connect
If your modem dials correctly, but the call never connects:
Verify that the phone number is correct and operational
and that the phone line to which the modem is attached
is not faulty.
To do this, unplug the modem from the telephone line and
plug in a regular telephone. Manually dial the number to
make sure that the modem on the other end of the line is
answering the call.
Listen carefully to your modem while it dials the call.
Some business phone systems require a pause between certain
numbers. Use a dash in the cu command to
indicate a pause of two seconds. For example, if you
9----4581234, the modem pauses
for 8 seconds after dialing the first number.
The dialer translates the dash passed to the cu
command into the appropriate code for your modem. For
example, the dialer translates the dash into a comma
before sending to an AT-compatible modem.
NO DEVICES AVAILABLE message
When you try to dial out on the modem,
the following message is displayed:
Connect failed: NO DEVICES AVAILABLE
To solve the problem:
Verify that the modem port has an entry in the
Here are example entries for an AT-compatible modem
running at 9600bps on /dev/tty1A:
ACU tty1A - 9600 /usr/lib/uucp/dialHA96V
Direct tty1A - 9600 direct
These lines must not being with pound signs (#) or whitespace.
Verify that the modem port in Devices has the
correct line speed associated with it. If you specify the
line speed with the -s option to cu,
verify that there is an entry in Devices that
corresponds to that line speed.
Modem answers, but terminal displays garbage
If the modem answers, but the terminal displays garbage
Verify that the site that you are calling is set to the
same data bit and parity values that you are using.
By default, cu uses 8 data bits, and no parity.
To change the values to 7 data bits and even parity, enter
cu -e. For 7 data bits and odd parity, use
cu -o, and use cu -oe for 7 data bits
and no parity.
Verify that the remote computer is set to the same line speed
that you are using.
If you are dialing into another UNIX system, you can force
the remote site to switch to the next line speed by sending
a break signal.
To send the break signal during the login sequence, enter:
Check for noise on your phone line.
Noise problems become more acute when operating at
higher speeds. Normally, when there is a problem with
line noise, garbage characters appear on the screen in
short bursts or continuously, as if a system on the other
end of the line is trying to send valid data.
DEVICE LOCKED message
UUCP and cu create a lock file named
the /usr/spool/uucp directory.
This file is used to prevent anyone else using
the modem connected to the serial device line
if it is already in use.
If the lock file is not removed after a connection has been closed,
the modem may not be setting Carrier Detect (CD) correctly.
root must remove the lock file before anyone can use
the modem again.
Modem does not hang up
If your modem does not hang up at the end of a call:
Verify that you are using a serial port with modem control that is
configured in the /usr/lib/uucp/Devices file and
that the ``ACU'' entry for the modem port comes
before the ``Direct'' entry for the direct line. If you
are using a non-modem control port, change the port to the
corresponding modem control port. For example, the modem
control port associated with tty1a is
Non-modem control ports should only be used with terminals,
and when configuring the modem.
If the CD (Carrier Detect) light on the modem
does not go off when the call is disconnected, check the
modem switches to verify that the modem is set to detect
the incoming carrier. If your modem is AT-compatible,
use the AT&C1 command.
This forces the carrier detect line to follow the presence
of a carrier on the phone line.
Check the modem switches to verify that the modem is set to
detect DTR (Data Terminal Ready). The modem
should hang up when DTR goes from high to low.
If the modem is AT-compatible, use the
Some modems have a switch that can be set to ignore
DTR; make sure that this switch is off.
If you get a double echo when you dial out on your modem,
check the setting for local echo. If local echo is
enabled, disable it.
Problems dialing in
© 2005 The SCO Group, Inc. All rights reserved.
SCO OpenServer Release 6.0.0 -- 03 June 2005