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Configuring and Managing External Modems
Testing the Modem Connection
DC-151
Cisco IOS Dial Technologies Configuration Guide
Testing the Modem Connection
To test the connection, send the modem the AT command to request its attention. The modem should
respond with “OK.” For example:
at
OK
If the modem does not reply to the at command, perform the following steps:
Step 1 Enter the show users EXEC command and scan the display output. The output should not indicate that
the line is in use. Also verify that the line is configured for modem inout.
Step 2 Enter the show line EXEC command. The output should contain the following two lines:
Modem state: Idle
Modem hardware state: CTS noDSR DTR RTS
If the output displays “no CTS” for the modem hardware state, the modem is not connected, is not
powered up, is waiting for data, or might not be configured for hardware flow control.
Step 3 Verify the line speed and modem transmission rate. Make sure that the line speed on the access server
matches the transmission rate, as shown in Table 13.
To verify the line speed, use the show run EXEC command. The line configuration fragment appears at
the tail end of the output.
The following example shows that lines 7 through 9 are transmitting at 115200 bits per second (bps).
Sixteen 28800-kbps modems are connected to a Cisco AS2511-RJ access server via a modem cable.
Router# show run
Building configuration...
Current configuration:
. . .
!
line 1 16
login local
modem InOut
speed 115200
transport input all
flowcontrol hardware
script callback callback
autoselect ppp
autoselect during-login
Table 13 Matching Line Speed with Transmission Rate
Modem Transmission Rate
(in bits per second)
Line Speed on the Access Server
(in bits per second)
9600 38400
14400 57600
28800 115200