Modem Autodiscovery

You can configure a line to expect a specific modem mode. If no modem is specified, the router attempts to autodiscover the type of modem to which it is attached. The router determines the type of modem by sending AT commands to the modem and evaluating the response. The router includes a modemcap database with information on the following modems:

■ U.S. Robotics Courier: usr_courier

■ U.S. Robotics Sportster: usr_sportster

■ Hayes Optima: hayes_optima

■ Global Village: global_village

Telebit t3000: telebit_t3000

Microcom: microcom_hdms, microcom_server

■ Cisco Systems: mica, cisco_v110

The specific modemcap entries found on a particular system will be determined by the hardware and Cisco IOS software version that is installed.

Note Whenever possible, configure the modem to eliminate the overhead of modem autodiscovery.

Any modems that are not currently supported in the list can be manually added to the list to be autodiscovered in future communication.

Here is a sample debug of how a router establishes synchronization with a modem:

RTA#

6dl9h:

TTYl :

Line reset by

"Virtual Exec"

6dl9h:

TTYl :

Modem : IDLE->HANGUP

6dl9h:

TTYl :

destroy timer

type 0

6dl9h:

TTYl :

destroy timer

type l

6dl9h:

TTYl :

destroy timer

type 3

6dl9h:

TTYl :

destroy timer

type 4

6dl9h:

TTYl :

destroy timer

type 2

6dl9h:

TTYl :

dropping DTR,

hanging up

6dl9h:

TTYl :

Set DTR to 0

6dl9h:

ttyl :

Modem: HANGUP-

>IDLE

6dl9h:

TTYl :

restoring DTR

6dl9h:

TTYl :

Set DTR to 1

6dl9h:

TTYl :

autoconfigure probe started

6dl9h:

TTYl :

Modem command

--AT&F&Cl&DîSO

6dl9h:

TTYl :

Modem configuration succeeded

6dl9h:

TTYl :

Detected modem speed 3 84 00

6dl9h:

TTYl :

Done with modem configuration

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