Table Of Contents
Cisco MICA Modem Dial Modifiers for
Cisco AS5300 and AS5800 Universal Access Servers
June 22, 2001
This feature module describes dial modifier support for Cisco MICA modems through enhanced Cisco MICA attention (AT) commands on Cisco AS5300 and Cisco AS5800 universal access servers.
This document includes the following sections:
Dial modifiers permit multi stage dialing for outbound modem calling through public (PSTN) and private switched telephone networks.
The Cisco MICA Modem Dal Modifiers feature is enabled by arguments to the ATD AT command. The AT prefix informs the modem that commands are being sent to it, and the D (dial string or dial) suffix dials a telephone number, establishing a connection. With Cisco MICA Modem Dal Modifiers running Cisco IOS Release 12.1(5)T or higher, you can enter the following dial modifiers after the D in your dial string: X, W, and the comma (,) character. These modifiers had been previously accepted without error but ignored in Cisco MICA modems.
In the following example dial string, the portion of the string before the X is dialed for the given line type used in your configuration. All digits after the X generate the appropriate DTMF tones.
The Cisco MICA Modem Dal Modifiers feature meets industry demands for multi role, multi application access server capabilities.
The Cisco MICA Modem Dal Modifiers feature is available as part of the listed standard features offered by the Cisco MICA modem platform and the AT command set contained within Cisco MICA modems.
•AT Command Set and Register Summary for MICA Six-Port Modules
•Cisco AS5x00 MICA 6-Port and 12-Port Modem Module Portware/Cisco IOS Software Compatibility Matrixes
•Cisco IOS Configuration Guide Master Index, Cisco IOS Release 12.1
•Cisco IOS Command Reference Master Index, Cisco IOS Release 12.1
•Release Notes for Cisco MICA Portware Version 188.8.131.52 on Cisco AS5x00 Universal Access Servers
Supported Standards, MIBs, and RFCs
No new or modified standards are supported by this feature.
No new or modified MIBS are supported by this feature.
To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to the Cisco MIB web site on Cisco Connection Online (CCO) at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.
No new or modified RFCs are supported by this feature.
You must be running Cisco IOS Software Release 12.1(5)T or higher.
See the following section for configuration tasks for the Cisco MICA Modem Dal Modifiers feature. Each task in the list is identified as either optional or required.
•Using X, W, and (,) Dial Modifiers (required)
•Verifying Modem Connection (optional)
Using W, X, and (,) Dial Modifiers
To send AT commands to the modem, you must first put the modem in AT command mode. Entering AT command mode involves a reverse Telnet procedure. Enter AT command mode from Cisco IOS privileged EXEC mode using reverse Telnet.
Note Cisco MICA does not support the modem at-mode commands used in Cisco IOS line configuration mode. Therefore, you cannot issue AT commands to Cisco MICA modems from the Cisco IOS command line.
Use these guidelines when you send AT commands to a modem:
•Commands are executed when you press Return or Enter.
•Command lines are limited to 128 characters, not including the AT prefix and return characters. Dial strings are limited to 49 characters.
•You can enter several commands on the same command line, as long as you do not exceed the 128-character limit. Enter commands with no spaces or separators between them. The commands are executed in the order in which they appear on the command line. If an individual command fails (system returns ERROR), any subsequent commands on that line are not executed.
•Certain commands work only if they are the last command on the line. Such commands include
A (answer), D (dial), H (hang up), Z (reset), and any command that takes time to execute or that does not return a result immediately.
•Spaces within AT commands are permitted anywhere except between the A and the T. For example, enter ATS0?, AT S0?, ATS 0?, but not A TS0?.
•Commands can be entered as uppercase, lowercase, or mixed case.
•Enter Ctrl-C (^C) to abort a partially entered command. The modem echoes ^C.
•Use the Backspace key (or another key specified in register S5) to erase characters on the command line, except for the leading characters AT. To clear the characters AT, press Return for a fresh command line.
•A missing numeric argument is assumed to be zero. For example, the Quiet command Q is equivalent to Q0.
•The modem operates in the following modes:
–Command state: The modem is idle and waiting for commands.
–Setup state: Establishing a connection.
–Online state: Connected to another modem. To return to the online state from any other state, enter ATO and press Return. You will see a fresh connect message.
–Escape state: Allows you to enter commands while the modem is online. To go to escape state, enter the +++ default escape code. When you enter the +++ command, pause for at least a second before and after typing it, but do not pause between characters. Do not press Return. Wait for the OK prompt before entering commands.
For more information about AT commands, refer to the Cisco document, AT Command Set and Register Summary for MICA Six-Port Modules.
Verifying Modem Connection
If you are unable to connect to the modem, check the following:
•Enter the show users EXEC command to verify that the modem state is idle. You should see that the line is not in use. Shows TTY reverse Telnet status information.
•Enter the show line EXEC command to verify that the line is configured for modem inout. Shows TTY reverse Telnet status information.
•Enter the show modem EXEC command and its variations to provide modem connection information. If you do not have any connected calls, the modem is idle and the display shows no (*) characters next to the modem.
•Check to see if the virtual terminal connections to lines in the access server require passwords.
•Check to see if the speed between the modem and the access server are the same. They are likely to be different. If they are different, switch off the modem, then switch it back on. This should match the speed of the modem with the speed of the access server.
Use example dial strings in this section as a guide.
•The following examples show a call placed to 555-1234 with a dial extension of 1234 after a wait of four seconds.
•The following examples show a call placed to 555-1234, with a wait of four seconds, then a dial to extension 71, which enables the dial tone for placing an outbound call. After detecting the outbound dial tone, a call to 555-0987 is placed.
•The following examples show a call placed to 555-1212 (which, for this example, provides a second dial tone for placing calls known as a call bridge) and then a wait for the dial tone indicated by the W. When the dial tone is detected, 555-1234 is dialed. There is no X in this PRI example, because the W will act as the delimiter to indicate to the CSM that there has been a transition to DTMF dialing.
This section documents the modified command that enables the Cisco MICA Modem Dal Modifiers feature. All other commands used with this feature are documented in the Cisco IOS Release 12.2 command reference publications.
To enable dial modifiers X, W, or the comma (,) character on Cisco MICA modems, use the ATD command in the command state AT command mode.
ATD [X | W |,]
No default behavior or values.
Command state AT command mode.
The W and (,) modifiers work similarly to those used in a standalone analog modem.
The W dial modifier monitors the audio content within the DS-0 channel. When the conditions of dial tone are detected, any numeric characters in the ATD string following a W are asserted as in-band. If the W is found in the remainder in the string, it is acted upon in accordance with its functional definitions.
The Cisco MICA dial tone detector is required to detect a normal, continuous dial tone. You can optionally set the dial tone detector to recognize a credit card dial tone, which is characterized by a short, one-time 500ms tone with a volume decay not lasting more than 500 ms. If no dial modifier is present in an ATD string, then all digits are passed to the Cisco IOS software for delivery to the Public Switched Telephone Network (PSTN), according to the specific type of trunk being used by the access server (channelized T-1, E-1, or primary rate ISDN).
If the ATD state is already in the in-band DTMF mode, any further digits appearing in the ATD string are sent as in-band DTMF tones. Once the state machine is in the in-band DTMF mode, it does not go back to the mode where digits are passed to the Cisco IOS software for trunk signaling.
The following shows a sample PRI call:
Number is dialed.
Switches to DTMF mode.
Dials the digits 71.
Waits for a dial tone.
A second number is dialed.
Note Depending on switch and equipment interactions, extra comma characters (,) might be required in the dial modifiers string.
AT command set—The modem command-line interpreter contained within Cisco MICA modems.
CSM—call switching module.
DTMF—dual tone multifrequency.
MICA—Modem ISDN channel aggregation. Used as a generic term to describe the Telebit high-density modem technology.
PRI—Primary Rate Interface. ISDN interface to primary rate access. Primary rate access consists of a single 64-Kbps D channel plus 23 (T1) or 30 (E1) B channels for voice or data.
PSTN—Public Switched Telephone Network.