System information

Troubleshooting Dialin Connections 16-353
Dialin: Modem Hangs Up Shortly After Connecting
Dialin: Modem Hangs Up Shortly After Connecting
Symptom: A dialin connection is successful but the modem hangs up after 30 to 90 seconds.
Table 16-5 outlines the problems that might cause this symptom and describes solutions to those
problems.
Table 16-5 Dialin: Modem Hangs Up Shortly After Connecting
Wrong telephone line attached to
remote modem
Step 1 Make sure you are using the correct telephone line. Replace the
remote modem with a telephone and call again. If the phone rings,
you are using the correct telephone line.
Step 2 Contact the telephone company to make sure that the line is good.
Remote modem not attached to a
router
Step 1 Make sure the remote modem is attached to a router or other device
that is asserting DTR.
Step 2 Most modems have an LED indicator for DTR. Check to make sure
this indicator comes on.
Possible Causes Suggested Actions
Modem speed setting
is not locked
Step 1 Use the show line exec command on the access server or router. The output
for the auxiliary port should indicate the currently configured Tx
1
and Rx
2
speeds.
For an explanation of the output from the show line command, see the section
“Using debug Commands” earlier in this chapter.
Step 2 If the line is not configured to the correct speed, use the speed line
configuration commands to set the line speed on the access server or router
line. Set the value to the highest speed in common between the modem and
the access server or router port.
To set the terminal baud rate, use the speed line configuration command. This
command sets both the transmit (to terminal) and receive (from terminal)
speeds.
Syntax:
speed bps
Syntax Description:
• bps—Baud rate in bits per second (bps). The default is 9600 bps.
Example:
The following example sets lines 1 and 2 on a Cisco 2509 access server to
115200 bps:
line 1 2
speed 115200
Note: If for some reason you cannot use flow control, limit the line speed to
9600 bps. Faster speeds are likely to result in lost data.
Step 3 Use the show line exec command again and confirm that the line speed is set
to the desired value.
Possible Causes Suggested Actions