ATMEL AT Commands Internal Modem Service Manual



AT Commands

for the Apple Internal Modem

K Apple Computer, Inc.

© 1998 Apple Computer, Inc. All rights reserved.

Under the copyright laws, this manual may not be copied, in whole or in part, without the written consent of Apple.
Your rights to the software are governed by the accompanying software license agreement.

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“keyboard” Apple logo (Option-Shift-K) for commercial purposes without the prior written consent of Apple may
constitute trademark infringement and unfair competition in violation of federal and state laws.

Every effort has been made to ensure that the information in this manual is accurate. Apple is not responsible for
printing or clerical errors.

Apple Computer, Inc.
1 Infinite Loop
Cupertino, CA 95014-2084
408-996-1010
http://www.apple.com

Apple and the Apple logo are trademarks of Apple Computer, Inc., registered in the U.S. and other countries.

Contents

1 Entering AT Commands 5

Typing an AT Command 5

Using Command Parameters 5

Entering Multiple Commands 6

Entering and Exiting Command Mode 6

2 AT Command Reference 7

3 S-Registers 29

4 Result Codes 45

5 Glossary 51

3

CHAPTER

1

1

Entering AT Commands

To enter an AT command, you must be using a terminal emulation application that provides
you with a text area for entering commands and receiving command feedback, such as
ZTERM and MacTerminal.

Typing an AT Command

The command line is made up of three elements: the prefix, the body, and the termination
character. The command line prefix consists of the characters “AT” or “at” or, to repeat the
execution of the previous command line, the characters “A/” or “a/” or, to escape from data
mode, the characters, “+++”.

For example, to answer an incoming call using the A (answer) command, you type

ATA

and then press the Return key.

Using Command Parameters

There are two type of commands: action commands and parameter commands. Action
commands may be “executed”, or “tested”. The parameter commands may be “set” or “read”.

Some parameter commands require a parameter, which is usually a single digit that
determines the command’s behavior. For example, the parameter n in the Hn command is
either 0 (to hang up) or 1 (to go off-hook).

To hang up using this command, you type

ATH0

and then press the Return key.

Some parameter commands require parameters that are not single digits. For example, the
Dn command accepts one or more single-character dialing modifiers, plus a telephone
number. To use touch-tone dialing (T) to dial the telephone number 123-4567, you type

5

ATDT1234567

and then press the Return key.

Entering Multiple Commands

You can enter multiple AT commands on the same line, as long as the line begins with “AT”
and ends with a carriage return.

You usually use multiple commands on the same line to configure your modem. For
example, to request that the modem use the factory default settings (&F command) and
display current configuration and stored profile (&V command), you type

AT&F1&V

and then press the Return key.

Entering and Exiting Command Mode

The modem must be in the command mode before you enter an AT command. If you are
connected to another modem, you can use the +++ command to switch to command
mode. (You can later return to your connection using the On command.)

For example, to enter an AT command when a connection is active, you type

+++

6 Chapter 1

to enter command mode; then type the AT commands you want to issue; and finally type

ATO

to return to your connection.

CHAPTER

2

2

AT Command Reference

AT commands control your modem’s settings and operation. This section provides detailed
information on all AT commands supported by the Apple internal modem.

+++ (switching to command mode)

The +++ command forces a modem that is already connected to enter the command
state, so you can send commands to your modem without breaking its connection with the
remote modem. In some cases, you must send “AT” after the +++ command. Unlike other
AT commands, the +++ command is not preceded by the “AT” prefix. The command is
accepted when the “+++” is typed, so you do not follow this command with a carriage
return.

In order to prevent the modem from responding to “+++” (called the “escape sequence”)
in transmitted data, it requires a one-second pause before and after the sequence. Without
the pause, the modem treats the “+++” sequence as data rather than a command.

You can change the escape sequence from +++ to another string of characters by setting
the S2 register. You can change the pause time required for the escape sequence by setting
the S12 register.

A (answering an incoming call)

The A command forces the modem to go off-hook in answer mode. Use this command to
manually answer an incoming call when you know that another modem is calling. When the
modem detects an incoming call, it sends the RING result code to your computer. If a
telecommunications application is active, the result code appears on your screen. For
example, to answer an incoming call, you type: ATA

A/ (repeating the last command)

The A/ command repeats the previous command. This command is especially useful for re­issuing a dial command that failed because of a busy line or no answer. Unlike other AT
commands, the A/ command is not preceded with the “AT” prefix. The command is accepted
as soon as the “A/” is typed, so you do not follow this command with a carriage return.

7

\An (setting maximum MNP block size)

When the modem establishes an MNP error-corrected connection, it will use the maximum
block size set by this command.

m \A0—64-character block size.
m \A1 (default)—128-character block size.
m \A2—192-character block size.
m \A3—256-character block size.

For example, to instruct the modem to use the default block size when negotiating an MNP
error-corrected connection, you type: AT\A1

Bn (specifying protocol for 300 or 1200 bps)

When the modem is configured to allow either option, the modem will select Bell or CCITT
protocols for 300 or 1200 bps according to the parameter supplied. Any other line speed will
use a CCITT protocol. The parameter value, if valid, is written to S27 bit 6. (Also, see ATFn
command.)

m B0 (default for modems sold outside the US)—Selects CCITT V.22 protocol for 1200 bps

connections and CCITT V.21 protocol for 300 bps connections.

m B1 (default for US modems)—Selects Bell 212A protocol for 1200 bps connections and

Bell 103 protocol for 300 bps connections.

8 Chapter 2

\Bn (Transmit Break to remote)

In non-error-correction mode, the modem will transmit a break signal to the remote modem
with a length in multiples of 100 ms according to parameter specified. If a number in excess
of 9 is entered, 9 is used. The command works in conjunction with \K command. In error­correction mode, the modem transmits a break signal of unspecified length through the
error-correction protocol. The default value is \B3, specifying a break signal length of 300 ms.

%Cn (selecting data-compression settings)

Enable or disable data compression negotiation. The modem can only perform data
compression on an error corrected link. The parameter value, if valid, is written to S41 bits 0
and 1.

m %C0—Disables data compression. Reset S46 bit 1.
m %C1—Enables MNP 5 data compression. Resets S46 bit 1.
m %C2—Enables V.42bis data compression. Sets S46 bit 1.
m %C3 (default)—Enables both V.42bis and MNP 5 data compression. Sets S46 bit 1.

&Cn (modifying the carrier detection response)

The modem controls the RLSD output. The parameter value, if valid, is written to bit 5 of the
S21 register.

m &C0—RLSD remains ON all the times.
m &C1 (default)—RLSD follows the state of the carrier.

Dn (entering a dialing string)

The Dn command causes the modem to dial a telephone number. n is the telephone number
you want to dial. The telephone number can include the characters 0–9, A–D, #, and * (A,
B, C, D, #, and * can be used only when touch-tone dialing is selected). Dashes,
parentheses, and spaces are ignored. For example, to dial the telephone number 123-4567,
you type: ATD 123-4567

Note: The space and dash in the telephone number are ignored.

Dialing Modifiers

You can also include a number of dialing modifiers in the n parameter to change the way
dialing is handled. The following dialing modifiers can be used with the Dn command:

! (flash on-hook)

The modem will go on-hook for the time specified by the S29 register and then back off­hook. This modifier can be placed anywhere in the dialing string.

Example: ATDT!123-4567

This command instructs the modem to go on-hook and back off-hook, and then use touch­tone dialing to dial the telephone number 123-4567.

@ (wait for silence)

The modem will wait for at least 5 seconds of silence after in the call progress frequency
band before continuing with the next dial string parameter. If the modem does not detect
five seconds of silence before the expiration of the call abort timer(S7), the modem will
terminate the call attempt with a NO ANSWER message. If busy detection is enabled, the
modem will terminate the call with the BUSY result code. If answer tone arrives during
execution of this parameter, the modem handshakes.

Example: ATD1234567@8888

This command dials the telephone number 123-4567, waits for the call to be answered, and
then dials the extension 8888.

, (dial pause)

The modem will pause for a time specified by S8 register before dialing the digits following
“,”.

AT Command Reference 9

Example: ATDT123-4567,,,888

This command uses touch-tone dialing to dial the telephone number 123-4567. It then
pauses for six seconds before dialing the telephone extension 888.

; (return to command mode after dialing)

The ; dialing modifier instructs the modem to return to command state after dialing a
number. You can use this modifier to issue additional AT commands while remaining off­hook. The semicolon must be placed at the end of the dial command, but can then be
followed by other commands.

Example: ATD1234567;X1DT,8

This command instructs the modem to dial the telephone number 123-4567 and then return
to command state. Once the modem is in command state, it pauses (indicated by the
comma) and then dials the number 8, without checking for a dial tone (X1).

& (wait for credit-card tone)

Wait for credit-card dialing tone before continuing with the dialing string. If the tone is not
detected within the time specified by the S7(US models) or S6(W-class), the modem will
hang up and generate an error message.

Example: ATDT123-4567&112233

This command dials the telephone number 123-4567 and then waits for a credit card tone
before dialing 112233.

10 Chapter 2

^ (enable calling tones)

The ^ dialing modifier enables calling tones for the current dial attempt. By default, calling
tones are disabled for Internal 56k modems sold in North America. You might want to enable
calling tones with the ^ modifier if, for instance, the device that you are calling uses calling
tones to differentiate between a voice, fax, or data call.

Example: ATDT^123-4567

This command instructs the modem to emit calling tones when the remote device answers
the call.

L (redial the last telephone number)

The L dialing modifier instructs the modem to redial the last telephone number dialed. The L
modifier must be placed immediately after the D in the Dn command. The modem ignores
any characters placed after the L modifier. To display the last-dialed number (with a terminal
emulation application), use the following command: ATDL?

Example: ATDT1234567
ATDL

The first command dials the telephone number 123-4567. The second command redials the
telephone number.

P (pulse dial)

The P dialing modifier instructs the modem to use pulse dialing. If you use P between the
digits of a telephone number, the digits following P are pulse-dialed.

Example: ATDP123-4567

This command uses pulse dialing to dial the telephone number 123-4567.

R (originate call in answer mode)

This command will be accepted, but not acted on.

T (touch-tone dial)

The T dialing modifier instructs the modem to use touch-tone dialing.

Example: ATDT123-4567

This command uses touch-tone dialing to dial the telephone number 123-4567.

W (wait for a dial tone)

The modem will wait for dial tone before dialing the digits following “W”. If dial tone is not
detected within the time specified by S7(US) or S6(W-class), the modem will abort the rest
of the sequence, return on-hook, and generate an error message.

Example: ATDT8W123-4567

This command instructs the modem to dial 8, then wait for a dial tone before dialing the
telephone number 123-4567.

&Dn (disconnecting using DTR signaling)

This command interprets the ON to OFF transition of the DTR signal from the computer. For
each parameter value, the way DTR is interpreted depends on the setting of the &Qn
command. When you enter a valid command parameter, it is written to S21 bits 3 and 4.

m &D0 (default)

m For &Q0, &Q5, &Q6: DTR is ignored (assumed ON). Allows operation with computers

that don’t provide DTR signaling.

m For &Q1: when DTR drops, the modem hangs up. Autoanswer is not affected.
m For &Q2, &Q3: when DTR drops, the modem hangs up. Autoanswer is inhibited.

m &D1

m For &Q0, &Q1, &Q5, &Q6: when DTR drops, the modem returns to the asynchronous

command state without disconnecting, as if the asynchronous escape sequence had
been entered.

AT Command Reference 11

m For &Q2, &Q3: when DTR drops, the modem hangs up.Autoanswer is inhibited.

m &D2

For &Q0–Q6: when DTR drops, the modem hangs up. Autoanswer is inhibited.

m &D3

m For &Q0, &Q1, &Q5, &Q6: when DTR drops, the modem performs a soft reset (as if

the Zn command had been received). The &Yn setting determines which profile is
loaded.

m For &Q2, &Q3: when DTR drops, the modem hangs up. Autoanswer is inhibited.

Example: AT&D2

This command enables DTR hangup for all values of the &Qn command.

En (turning echo on and off)

The En command controls whether commands that you type are echoed back to your
computer while the modem is in command mode.

m E0—Disables echo to the computer in command mode.
m E1 (default)—Enables echo to the computer in command mode.

Example: ATE1

This command instructs the modem to echo characters it receives from the computer while
in command mode.

12 Chapter 2

%En (Enable/Disable Line Quality Monitor and Auto-Retrain or
Fallback/Fall Forward)

The %En command controls whether the modem will automatically monitor the line quality
and request a retrain (%E1) or fall back when line quality is insufficient or fall forward when
line quality improves (%E2).

m %E0—Disables line quality monitor and auto-retrain.
m %E1—Enables line quality monitor and auto-retrain.
m %E2 (default)—Enables line quality monitor and fallback/fallforward.

Example: AT%E1

This command tells the modem to monitor the line quality and request a retrain if the quality
changes.

&Fn (loading a factory configuration)

The modem loads the factory default configuration(profile). The factory default are
identified for each command and in the S-register description. A configuration (profile)
consists of a subset of S-Registers.

m &F0 (default)—Restores factory configuration 0.
m &F1—Restores factory configuration 1.

&Gn (selecting the guard tone)

The &Gn command determines whether the modem transmits a guard tone when
answering. The parameter value, if valid, is written to S23 bits 6 and 7.

m &G0—Disables guard tones (US default).
m &G1—Disables guard tones.
m &G2—Selects 1800 Hz guard tone.

Hn (disconnecting)

You use the Hn command to place the modem on-hook (hang up) or take the modem off­hook (equivalent to lifting the telephone receiver).

m H0—Places the modem on-hook (hangs up).
m H1—Takes the modem off-hook and places it in command mode.
m +++

Example: ATH0

Suppose that you want to end a connection that you have established with another modem.
This example uses the +++ command to enter command mode, then uses H0 to hang up.

In (displaying information about the modem)

The In command instructs the modem to provide information about itself.

m I0—Reports product code, e.g., 56000
m I1—Reports the least significant byte of the stored checksum in decimal (see firmware

release notes), e.g., Apple Version 0003,6/14/98

m I2—Reports OK if ROM checksum is valid; otherwise, reports ERROR.
m I3—Reports firmware identification codes.
m I4—Reports OEM defined identifier string, e.g., Apple Internal Modem
m I5—Reports the Country Code parameter, e.g., 008
m I6—Reports modem data pump model and internal code revision, e.g., RCV56DPF-PLL

28571A Rev 24.00/24.

AT Command Reference 13

\Jn (enabling DTE rate adjustment)

If you have a European modem, you can control whether the modem adjusts the DTE speed
to match the line speed after making a connection. It is recommended that you disable the
adjustment of the DTE speed to match the line speed (\J0). Most telecommunications
applications automatically set the DTE speed to the optimum rate of data transfer, which is
often higher than the line speed.

m \J0 (default)—Disables adjustment of the DTE speed to match the line speed.
m \J1—Enables adjustment of the DTE speed to match the line speed.

Example: AT\J0

This command instructs the modem to disable adjustment of the DTE speed to match the
line speed.

Kn (controlling the flow control method)

You use the &Kn command to select the flow control method used for a connection between
a computer and a modem. When you enter a valid command parameter, it is written to bits
0–2 of the S39 register.

m &K0—Disables flow control.
m &K3 (default)—Enables hardware flow control (RTS/CTS).
m &K4—Enables software flow control (XON/XOFF).
m &K5—Enables transparent XON/XOFF flow control.
m &K6—Enables both RTS/CTS and XON/XOFF flow control.

14 Chapter 2

\Kn (controlling break signal behavior)

The \Kn command controls the behavior of the modem when it receives a break signal. The
meaning of each parameter value depends upon the context of the break signal.

Receiving a break from the computer (in on-line mode)

This section describes, for each parameter value, what the modem will do when it receives a
break signal from the computer while in on-line mode.

m \K0—Enter on-line command mode, without sending a break to the remote modem.
m \K1—Clear data buffers and send break to the remote modem.
m \K2—Same as \K0.
m \K3—Send break to the remote modem immediately.
m \K4—Same as \K0.
m \K5 (default)—Sends break to remote modem in sequence with transmitted data.

Receiving a break from the computer (in command mode)

This section describes, for each parameter value, what the modem will do when it receives a
break signal from the computer while in command mode.

m \K0—Clear data buffers, then send a break to the remote modem.
m \K1—Same as \K0.
m \K2—Send break to the remote modem immediately.
m \K3—Same as \K2.
m \K4—Send a break to the remote modem in sequence with transmitted data.
m \K5 (default)—Same as \K4.

Receiving a break from the remote modem

This section describes, for each parameter value, what the modem will do when it receives a
break signal from the remote modem during a non-error-correcting connection.

m \K0—Clear data buffers, then send a break to the computer.
m \K1—Same as \K0.
m \K2—Send break to the computer immediately.
m \K3—Same as \K2.
m \K4—Send break to the computer in sequence with received data.
m \K5 (default)—Same as \K4.

Example: AT\K5

This command resets the modem to its default break signal behavior:
m When the modem receives a break from the computer, it sends a break to the remote

modem in sequence with data.

m When the modem receives a break from the remote modem, it sends a break to the

computer in sequence with data.

-Kn (enabling V.42 to MNP 10 conversion)

You use the -Kn command to enable or disable the conversion of a V.42 LAP-M connection to
an MNP 10 connection. When you enter a valid command, its parameter value is written to
bits 0–1 of the S40 register.

m -K0 (default)—Disables V.42 LAP-M to MNP 10 conversion.
m -K1—Enables V.42 LAP-M to MNP 10 conversion.
m -K2—Enables V.42 LAP-M to MNP 10 conversion; inhibits the initiation of MNP extended

services during V.42 LAP-M answer mode detection phase.

AT Command Reference 15

Ln (adjusting the speaker volume)

You use the Ln command to adjust the modem speaker volume. (If you want to turn the
modem speaker on or off, see the Mn command.) The parameter value, if valid, is written to
S22 bits 0 and 1.

m L0—Lowest speaker volume.
m L1 (default)—Low speaker volume.
m L2—Medium speaker volume.
m L3—High speaker volume.

%L (reporting the line signal level)

Returns a value which indicates the received signal level. The value returned is a direct
indication (DAA-dependent) of the received level at the MDP, not at the telephone line
connector. For example, 009 = –9 dBm, 043= -43 dBm, and so on.

Mn (turning the speaker on or off)

You use the Mn command to turn the modem speaker on or off. (If you want to change the
speaker volume, see the Ln command.) The parameter value, if valid, is written to S22 bits 2
and 3.

m M0—Speaker is always off.
m M1 (default)—Speaker is on during call establishment, until the modem detects a carrier

tone.

m M2—Speaker is always on.
m M3—Speaker is off during receiving carrier and dialing, but on during answering.

16 Chapter 2

&Mn (selecting asynchronous mode)

You can use the &Mn command to determine the DTR operating mode. The modem treats
the &Mn command as a subset of the &Qn command.

m &M0—Selects direct asynchronous operation.

Note that the command sequence “&M0\N0” selects normal buffer mode, but the
command sequence \N0&M0 select direct mode. This is because the \N0 command is
analogous to the &Q6 command. The value 000b is written to S27 bits 3,1 and 0.

m &M1—Selects synchronous connect mode with async off-line command mode. The value

001b is written to S27 bits 3, 1, and 0, respectively. (Serial interface operation only.)

m &M2—Selects synchronous connect mode with async off-line command mode. Same as

&M1 except that &M2 enables DTR dialing of directory slot 0. The modem will disconnect
if DTR is OFF for more than the period in S25 (in units of hundredths of a second): the
data connection will be synchronous. The value 010b is written to S27 bits 3, 1, and 0,
respectively. (Serial interface operation only.)

m &M3—Selects synchronous connect mode. This mode allows DTR to act as a talk/data

switch. The call is manually initiated while DTR is inactive. When DTR becomes active, the
handshake proceeds in originate or answer mode according to S14 bit 7. The value 011b
is written to S27 bits 3, 1, and 0, respectively. (Serial interface operation only.)

+MS (Select Modulation)

This extended format command selects the modulation and, optionally, enables or disables
automode, specifies the lowest and highest receive rates, selects _-Law or A-Law codec type,
and, specifies the highest transmit rate using one to five subparameters. The command
format is:

+MS= <mod>
,[<automode>][,[<min_RX_rate>][,[<max_RX_rate>][,[<x_law>][,[<reserved>],
[<max_TX_rate>]]]]]]<CR>

Notes:

1. For 14400 bps and lower speeds, the Nn command and S37 register can alternatively be
used, in which case the +MS subparameters will be modified to reflect the Nn and
S37=x settings. Use of the Nn and S37=x commands is not recommended but is
provided for compatibility with existing communication software. (S37 is not updated by
the +MS command.)

2. Subparameters not entered (enter a comma only or <CR> to skip the last
subparameter) remain at their current values.

Reporting Selected Options

The modem can send a string of information to the DTE consisting of selected options using
the following command: +MS?

The response is:

+MS:
<mod>,<automode>,<min_RX_rate>,<max_RX_rate>,<x_law>,<reserved>,
<max_TX_rate>

For example:

+MS: 56,1,300,56000,0,0,33600 [default for RC56 with V.90/K56flex or K56flex only loaded]

+MS: 12,1,300,56000,0,0,33600 [default for RC56 with V.90 only loaded]

+MS: 11,1,300,33600,0,0,33600 [default for RC336]

Reporting Supported Options

The modem can send a string of information to the DTE consisting of supported options
using the following command: +MS=?

The response is:

AT Command Reference 17