# Modem Information

This section provides the following information:

- Introduction to the Modem
- Modem Speeds and Protocols
- How to Use AT Commands
- Frequently Used AT Commands
- Updated Modem Information

## Introduction to the Modem

Once the PRO/Wireless Mobile Adapter has been installed, using the instructions under Installation, most users will rely on a communications application program such as HyperTerminal to configure the modem and carry out communications and fax tasks. Interaction with the modem will usually be handled by the communications software.

However, some communications programs require the user to input certain types of modem commands. And some users prefer to configure the modem manually without the aid of their communication software's menus and prompts. Technical information is provided in this section to support both of those situations.

For help in solving problems that occur after the modem has been installed, see Troubleshooting.

## Modem Speeds and Protocols

PRO/Wireless Mobile Adapter models support both V.90 and K56flex standards for 56K data transmission. Downloading of information and E-mail from corporate networks or the Internet can occur at speeds of up to 56Kbps over standard phone lines. Data sent by the user to the network travels at the highest available V.34 rate (up to 33.6Kbps). In order to achieve 56Kbps download speeds, the modems at both ends of the connection must support the V.90 or K56flex standard. Otherwise a standard V.34 connection will be negotiated. Current U.S. Federal Communications Commission (FCC) regulations limit download speeds to 53Kbps.

Intel modem firmware is designed to initially attempt to make a V.90 connection, and then fall back to K56flex if the computer being dialed does not support V.90. However, there are other factors that could affect your ability to achieve 56Kbps transmissions.

### How 56K Modem Technology Works

This modem uses 56K modem technology to reach speeds up to 56 Kbps.* 56K modem technology enables users to access information and email on corporate networks, the Internet, and other online services at speeds up to 56 Kbps over standard phone lines.

The 56 Kbps modem technology utilizes the fact that today's telephone network infrastructure is primarily digital. With this new technology, speeds up to 56 Kbps can be achieved downstream (when downloading data from the "Host" modem) when all of the following conditions are met:

1. The line must be digitally terminated at the host side.

2. The connection can only go through a single digital-to-analog conversion (which means that satellite transmission and communications through digital PBXs will not operate at 56Kbps).

3. There must be two compatible modems: one at the Host and one on the computer. For your Intel modem, this means that the Host modem must support the V.90 standard or K56flex† technology.

### Different Types of 56K Technologies and the V.90 Standard

There are different types of 56K technologies available today. Your Intel modem is V.90 and K56flex compatible. This means that your Intel modem can connect at speeds up to 56K with any brand of V.90 modem. If the modem is not V.90 compatible, it must be K56flex compatible to reach 56K speeds. When connecting with non-56K speed modems, your Intel modem connects at speeds to 33.6 Kbps.

* 56 Kbps refers to server download speed only, and requires V.90 compatible modems at both the user and server sites. Download speeds of 56K are currently unavailable in the U.S. Other country-specific regulations may impose similar limits. For additional technical information on K56flex, go to http://www.intel.com/network/white_papers/56k.htm.

### Improving 56K Connections

First, check the Intel Web site for modem firmware updates (see Hint below). Second, check with your service provider to verify that they are using the latest V.90 technology compatible with the Intel modem.

In addition, there are two different modem settings you can change to improve your V.90 connections. These commands can be added to an application's initialization string or sent directly to the modem by using any communications or terminal application. When sending the commands by themselves, start the command with AT (example: AT+MS=V34), and press the Enter key. When adding the command to an application's initialization string, the "AT" should already be present.

### Changing Top Speed (+MS Modulation Selection) Command

You can set the top speed at which your modem attempts to negotiate. The default is V.90 (32000 to 56000 bps).

| If you routinely try to connect to non-56K modems or are having trouble establishing connections, then try to lower the "top speed" by changing the +MS setting to +MS=V34 or lower.

  +MS=V90 | V.90 (32000 to 56000 bps) default
  +MS=K56 | K56flex (32000 to 56000 bps)
  +MS=V34 | V.34 (2400 - 33600 bps)
  +MS=V32B | V.32bis (4800 - 19200 bps)
  +MS=V32 | V.32 (4800 or 9600 bps)
  +MS=V23C | V.23 with constant carrier (1200/75 or 75/1200 bps)
  +MS=V22B | V.22bis (2400 bps)
  +MS=V22 | V.22 (1200 bps)
  +MS=V21 | V.21 (300 bps)
  +MS=B212 | Bell 212A (1200 bps)
  +MS=B103 | Bell 103 (300 bps)

### Change Setting For Particular Type of Location (S108 - Digital Loss Selection) Command

Depending on your type of location, the S108 setting can be changed to improve the likelihood of obtaining a V.90 connection. S108 changes how digital loss is to be used during a V.90 connection.

| If you are connecting at speeds greater than 33.6Kbps, but want to get closer to a top speed of 56Kbps, try changing your S108 setting. Different settings may improve your connection speed, depending on your type of location.

  S108=0 | 0 dB digital loss (with no robbed bit signaling)
  S108=1 | 3 dB digital loss (recommended for use with PBX systems)
  S108=2 | 2 dB digital loss
  S108=3 | 3 dB digital loss (normal)
  S108=6 | 6 dB digital loss (recommended for long distance, default setting)
  S108=7 | 0 dB digital loss

## How to Use AT Commands

Some communications programs require direct input of modem commands, and some users prefer to configure the modem manually without the aid of their communication software's menus and prompts. These operations are performed by typing alphanumeric commands on the screen while the modem is in command mode, using AT Commands and S-Registers.

#### Initialization Strings

The modem initialization string is an AT command line containing modem parameter settings. The CardBus Modem is configured with a factory-default initialization string that can be restored at any time with the AT command AT&F. These settings may be suitable for some communications packages, while others may have custom requirements.

Modem operating modes

The Intel modem has two operating states: command mode and online mode.

Command mode

The modem "wakes up" in command mode when it is powered on and modem software is loaded. Only in command mode does the modem accept and execute typed commands. The modem automatically switches from command to online mode when a connection is established with another modem.

Use the command AT$ to see the complete set of available modem commands.

Limitations of command mode

Command mode operations with most modems, including the Intel modem, do not include sending or receiving files or faxes or logging on to a remote computer or network. Command mode can only be used to configure the modem and establish or break a connection. For all data communications and fax tasks you will also need appropriate equipment and applications software at both ends of the line.

Online mode

Online mode is the operating state the modem automatically switches to when a connection is established with another modem. If commands are typed in when the modem is in online mode and connected to another modem, they are not treated as commands but are sent as data to the other end of the connection. The exception is the "Escape" command (+++), which allows you to switch from online to command mode during a session with a remote modem without losing the connection.

The AT command set

The Intel modem uses a Hayes and Microcom compatible command set for modem operations in command mode. This is an extended "AT" command set in which most command strings start with the letters AT and commands are executed by pressing the Enter key at the end of the command line. Use the command AT$ to see the complete set of available modem commands.

S-Registers

In conjunction with the AT command set, the modem also makes use of a series of programmable memory storage locations called S-Registers. These S-Registers contain values that govern the operation of the modem and the performance of many of the AT commands. For more information about S-Registers, see Modem Speeds and Protocols.

The Escape and ATO commands

The Escape command used with the Intel modem is executed by typing three ASCII characters (default is "+++"). This command is used to return temporarily to command mode during connection to a remote modem.

The ASCII character is set with S-Register S2. The default is S2=43 (the + sign). Values 0-127 can be used. To disable this command, use an ASCII value greater than 127.

To return to online mode, type the command ATO (where O is the letter O), followed by Enter.

Fax commands

All fax operations require the use of fax software for configuration and execution of the appropriate fax and modem commands. This software switches the modem into fax mode, manages the fax process, and switches the modem back to its default data mode when the fax operation is complete.

See your fax software documentation for instructions on how to set up fax software and send or receive faxes.

#### Sending commands to the modem

AT commands can be executed only when the modem is in command mode. They are initiated by sending an attention code to alert the modem that commands are on the way. The AT attention code is followed by the appropriate command or commands, which can be in upper or lower case characters, or a combination of the two.

With two exceptions, all the commands issued to the modem must begin with AT and end with the Enter key. The exceptions are the Repeat command (A/), which executes as soon as you type /, and the Escape command +++, which executes as soon as three plus signs are typed.

Command parameters

Commands issued to the modem can be a single command such as AT&V or a sequence of commands such as AT &F S7=30 V1 X4 DT 1 213 555 2345. This line of characters is called the command line. The command line must be terminated by pressing the Enter key.

Commands can be up to 255 characters long, not counting the AT command prefix, any spaces used within the command line, any linefeed characters, or the terminating Enter key. Parentheses and hyphens are counted as command characters. Any attempt to create a command line of more than 255 characters in length results in an ERROR message. In this case the entire command line will be ignored by the modem.

Use the Backspace key (or the sequence Ctrl-H) to correct errors in typing the command string. You cannot delete the AT attention code. Press Ctrl-X to instruct the modem to ignore the entire command line and return to command mode. The modem responds by displaying OK without executing any of the command.

Command processing

The modem displays OK in response to commands it understands and can act upon, and ERROR in response to commands it does not understand or cannot execute. These command acknowledgment messages are called result codes. In addition to OK and ERROR, the modem can also respond with CONNECT, BUSY, NO CARRIER, RING, NO DIALTONE, and so on.

## Frequently Used Modem Commands

Below are some frequently-used AT commands. Using these sample commands, you can easily instruct the modem to dial and connect to another modem, to the Internet, or to a corporate network. Unless it is specifically stated otherwise, all the sample commands that follow must be preceded by the letters AT in all upper or all lower case and be executed by pressing the Enter key at the end of the command line.

Escape

+++ Escape. This command switches the modem's operating mode from online state to command state.

A response of OK after you have entered the +++ command from your communications program indicates that the modem is now in the command state and will accept AT commands. This command does not need to be preceded by the AT command prefix or terminated by Enter.

Dialing

The command that causes the modem to dial a number is the AT command ATDn. The n in this case represents a string of characters whose length is limited only by the capacity of the modem's command buffer. The command buffer can accommodate up to 255 characters in the dial string.

Handshaking

When you enter a Dial command and the modem successfully detects the distant modem's carrier signal, it attempts to negotiate a common data transmission rate and other transmission parameters based on the settings previously issued to both the sending and receiving modems. This negotiation, usually accompanied by a characteristic series of squeaks and squawks from the modem speaker, is called handshaking.

Dial modifiers

The Dial command has a variety of options, called dial modifiers, that are made up of specific letters and symbols and can be typed in any combination immediately following the Dial command. These dial modifiers allow you to control how a number is dialed.

For example, the command ATD P 9 W T 1 213 555 3456 instructs the modem to:

Go off-hook (pick up the phone) and detect dial tone

Pulse dial a 9

Wait for a second dial tone

Tone dial 12135553456 and wait for carrier detect

The P, W, and T are dial modifiers. Use the command AT$ to see the complete set of available modem commands.

Another frequently-used dial modifier is the comma. The inclusion of a comma (,) in the command line causes the modem to pause briefly before processing the next character or symbol in the line.

For example, the command ATD 9, P 555-3333 could be used to dial a 9 using tones to get an external line through a PBX, pause long enough to get the external dialing tone and then pulse dial 555-3333.

The command ATDL redials the last number dialed.

Repeat

A/ Repeat. This command does not require the AT prefix and executes when / is typed. The Enter key is not required. A/ causes the modem to re-execute the command line currently stored in the command buffer, which is usually the last command line entered. This is useful for redialing telephone numbers that had previously returned a BUSY result code.

For example, if you entered the command ATD 9, P 1-804-555-3333 and the modem responded by displaying BUSY on your monitor screen, you do not have to retype the command string to redial. Simply type A/ and the modem will reprocess the entire command line.

Hang Up

ATH Hang Up. This command instructs the modem to go "on-hook" or to hang up. Typing ATH hangs up the modem and disconnects the telephone line.

Help

AT$ Help. This command displays a multi-screen summary of all the modem's commands.

## Updated Modem Information

Download software, firmware, and country-specific upgrades from:
http://www.intel.com/support/network

### Parts and Accessories

For the most-recent list of PRO/100 Combo adapter cables and accessories, visit:
http://www.intel.com/support/network/adapter/24188.htm

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