USR AT COMMANDS

Data and General Commands

Every command except A/, +++, and A> must begin with the AT prefix and be executed by pressing ENTER.

Example: ATDL <ENTER> dials the last number called.

Command

+++

DS=n

Sr=n

#CID=n

#UD

%En

&An

&Bn

&Cn

&Dn

&Fn

&Gn

&Hn

&Kn

&Mn

&Nn

&Pn

&Sn

&Tn

&Wn

&Yn

&Zn=s

\An

\Bn

\Gn

+A8E=n

+A8E?

+A8T=n

+A8T?

+DCS=n

+DR=n

+DS=n

+DS44=n

+EB=n

+ER=n

+ESA

+GCAP

+GCI=n

+ILRR=n

+IPR=n

+ITF=n

+MR=n

+MS=n

+VCID=n

Function

Escapes to online-command mode. Does not require the ATprefix or a carriage return.

Displays help for basic commands.

Manual Answer. Goes off hook in answer mode. Pressing any key before the connection is complete aborts the operation.

Re-executes the last issued command. Used mainly to redial. Does not require the AT prefix or a carriage return.

Re-executes the last issued command continuously until the user intervenes or the command is executed forever. Does not require the AT prefix or a carriage return.

Set handshaking options.

Dials the specified phone number. After ENTER is pressed, pressing any key before the connection is complete aborts the operation. The default dialling method is tone (ATDT).

Dials the phone number string stored in NVRAM at position n. Phone numbers are stored with the &Zn=s command.

Sets local echo.

Controls hook functions.

Displays the information associated with n.

Controls speaker volume.

Note:Modem does not have a speaker.

Command is included for compatibility.

Operates speaker.

Controls modulation handshake

Returns online.

Sets pulse dialling (rotary dialling).

Displays/suppresses result codes.

Sets S-register r to the value n. For register values, see S-Registers.

Sets DTMF tone dialling.

Displays verbal/numeric result codes.

Enables tone detection options.

Sets result codes displayed.

Selects reset default configuration.

Resets modem.

Controls Caller ID.

Displays Unimodem Diagnostics.

Displays numbers in blacklist. (Country selection must support blacklist.)

Controls Fallback/Fallforward.

Enables/disables added result code subsets (see Xn).

Manages the modem's serial port rate.

Controls Carrier Detect (CD) signal.

Controls Data Terminal Ready (DTR) operations.

Resets the modem and loads a read-only (non-programmable) factory configuration.

Sets Guard Tone.

Sets Transmit Data (TD) flow control.

Enables/disables data compression.

Sets Error Control (ARQ) for connections at 1200 bps and higher.

Sets S registers to attempt forced speed.

Sets the make-to-break ratio.

Sets the Data Set Ready (DSR) option.

Sets test modes.

Stores current configuration in NVRAM template.

Sets break handling.

Stores phone number string s in NVRAM at position n.

Selects maximum MNP block size.

Sends break.

Sets modem port flow control.

Sets XON/XOFF pass through.

Sets V.8 operation.

Display the current settings for V.8 or V.8 bis negotiation.

Sends a V.8 bis signal or message from the local DCE when V.80 is enabled

Displays the current +A8T setting.

Selects the data compression algorithm.

Controls data compression reporting.

Configures the V.42 bis data compression method.

Configures the V.44 data compression method.

Determines the action taken when a break is received.

Controls error control reporting.

Sets up error control parameters.

Displays supported capabilities.

Sets the country code.

Controls port rate reporting.

Displays DTE to DCE transmission rates.

Sets the transmit flow control thresholds.

Controls modulation reporting.

Controls modulation.

Controls Caller ID.

Default

None.

B1 when the modem is at 1200 bps.

B16 when the modem is at 300 bps.

None.

%E2

&A3

&B1

&C1

&D2

None.

&G0

&H1

&K1

&M4

&N0

&P1

&S0

None.

&Y1

None.

\A3

\B3

\G0

\X0

+A8E=1,1,C1,1

None.

+DCS=1,1

None.

+DS=3,0,1024,32

+DS44=3,0,0,1024,1024,

255,255,5120,4096

+EB=0,,30

+ER=0

None.

+ILRR=0

None.

+MS=V92,1,31200,

56000,31200,56000

+VCID=0

Options

None.

B2, B3

B15

B16

Selects CCITT V.22 mode when the modem is a 1200 bps.

Selects Bell 212A when the modem is at 1200 bps. Use only if the modem is not required to answer V.34-type calls.

Deselects V.23 reverse channel.

Selects V.21 when the modem is at 300 bps.

Selects Bell 103J when the modem is at 300 bps.

The maximum length of a dial string is 60 characters.

D0–D9

D#, D*

DL?

Numeric digits.

Extended touch-tone pad tones.

Dials the last phone number dialled.

Displays last phone number dialled.

Pulse (rotary) dial.

Tone (DTMF) dial

Waits for second dial tone (X2 or X4); linked to S6 register.

(Exclamation point) Flashes the switch hook.

(Comma) Pauses. Linked to S8 register.

(Slash) Delays for 125 ms. before proceeding with dial string.

(Semicolon) Returns to Command mode after dialling.

Dials, waits for quiet answer, and continues (X3 or higher).

(Quotation mark) Dials with alphabetic letters between quotes converted to numbers.

(Circumflex) Disables data calling tone transmission.

0–2

I11

I92

Modem does not display keyboard commands.

Modem displays keyboard commands.

Modem goes on-hook.

Modem goes off-hook.

Four-digit product code.

Results of ROM checksum.

Results of RAM checksum.

Product type.

Current modem settings.

Nonvolatile memory (NVRAM) settings.

Link diagnostics.

Product configuration.

Plug and Play information.

Extended link diagnostics.

V.92 settings.

Low.

Medium.

High.

Speaker always OFF.

Speaker ON until CONNECT.

Speaker always ON.

Speaker ON after dial, until CONNECT.

When originating or answering, this is for handshake only at the communication standard specified by register S37 and the B<value> command.

When originating or answering, this is for handshake only at the communication standard specified by register S37 and the B<value> command. During handshake, may fall back to a lower speed.

Returns online from command mode.

Returns online and retrains.

None.

All subsequent D<dial_string> commands use pulse dialling until either the T command or a tone dial modifier is received by the modem.

The modem uses tone dialling by default.

Displays result codes.

Quiet mode; does not display result codes.

None.

The modem uses tone dialling by default.

Displays numeric result codes.

Displays verbal result codes.

CONNECT result code reports DTE receive speed. Disables protocol result codes.

CONNECT result code reports DTE receive speed. Enables protocol result codes.

CONNECT result code reports DCE receive speed. Enables protocol result codes.

This command enables tone detection options used in the dialling process. As each function is chosen, the modem’s result codes are also affected. Therefore, this command is frequently used to control the modem’s responses. The primary function of this command is to control call response capabilities.

#CID=0

#CID=1

#CID=2

Selects stored profile (&W).

Selects factory configuration 0 (&F0).

Selects factory configuration 1 (&F1).

Selects factory configuration 2 (&F2).

Resets the modem to NVRAM profile selected by Y command.

Resets the modem to the stored profile (&W).

Resets the modem to factory default profile 0 (&F0).

Resets the modem to factory default profile 1 (&F1).

Resets the modem to factory default profile 2 (&F2).

Disables Caller ID.

Enables formatted Caller ID.

Enables unformatted Caller ID.

None.

%E0

%E1

%E2

&A0

&A1

&A2

&A3

&B0

&B1

&C0

&C1

&D0

&D1

&D2

&D3

&F0

&F1

&F2

&G0

&G1

&G2

&H0

&H1

&H2

&K0

&K1

&M0

&M4

&M5

Fallback/Fallforward disabled.

Fallback enabled, Fallforward disabled.

Fallback/Fallforward enabled.

ARQ result codes disabled.

ARQ result codes enabled.

V.xx modulation indicator added.

Protocol indicators added: LAPM/MNP/NONE (error control) and V42bis/MNP5 (data compression).

Serial DTE rate is variable, follows connection rate.

Fixed DTE rate.

CD override.

Normal CD operation.

Data Terminal Ready (DTR) override.

DTR toggle causes online Command mode.

Normal DTR operation.

Resets on receipt of DTR.

Loads a generic template.

Loads the hardware flow control template.

Loads the software flow control template.

No guard tone, U.S. and Canada.

550 Hz guard tone; requires B0 setting.

1800 Hz guard tone; requires B0 setting.

Flow control disabled.

Hardware flow control, Clear to Send (CTS).

Software flow control, XON/XOFF.

Data compression disabled.

Auto enable/disable.

Normal mode, error control disabled.

Auto Normal/ARQ.

ARQ required for connection.

&P0

&P1

&P2

&S0

&S1

&T0

&T1

&T3

U.S. ratio: 39%–61% at 10 pulses per second

UK ratio: 39%–61% at 10 pulses per second

UK ratio: 39%–61% at 20 pulses per second (Japan)

DSR override. DSR is always on.

DSR comes on after establishing a connection and goes off when the connection ends.

Ends testing.

Local Analogue Loopback (LAL).

Local Digital Loopback (LDL).

&W0

&Y0

&Y1

&Y2

&Y3

0–2

\A0

\A1

\A2

\A3

1–9

\G0

\G1

\X0

\X1

Destructive, but doesn't send break.

Destructive, expedited.

Nondestructive, expedited.

Nondestructive, unexpedited.

Example: AT&Z1=18005551212 stores the phone number 18005551212 in position 1. Use the DS=n command to recall and dial the number.

64 characters.

128 characters.

192 characters.

256 characters.

Expressed in hundreds of milliseconds.

The modem processes XON/XOFF flow control characters locally.

The modem passes XON/XOFF flow control characters.

The modem processes XON/XOFF flow control characters locally.

The modem passes XON/XOFF flow control characters.

This is a compound parameter. The full syntax is as follows:

+A8E=<v8o>,<v8a>,<v8cf>,<v8b>

<v8cf> contains the V.8 CI signal call function octet. Valid values are 0–FF.

Displays a list of valid +A8E settings.

None.

This is a compound parameter. The full syntax is as follows:

+A8T=<signal>,<1st message>,<2nd message>,<sig en>,<msg en>,<supp delay>

Displays a list of valid +A8T settings.

None.

This is a compound parameter. The full syntax is as follows:

+DCS=<v42bis>,<v44>

Disables the compression report.

Enables the compression report.

Displays a list of valid +DR settings.

This is a compound parameter. The full syntax is as follows:

+DS=<direction>,<compression_negotiation>,<max_dict>,<max_string>

For this modem, only direction is variable. The fixed values of the other parameters is as follows:

This is a compound parameter. The full syntax is as follows:

<direction>,<compression_negotiation>,<capability>

,<max_codewords_tx>,<max_codewords_rx>, <max_string_tx>,<max_string_rx>,<max_history_tx>,<max_history_rx>

The value of compression_negotiation is always 0 (never disconnects if V44 is not negotiated).

The value of capability is always 0 (Stream method).

This is a compound parameter. The full syntax is as follows:

<break_selection>,<timed>,<default_length>

This modem does not support the timed parameter.

Valid values for <default_length> are 30–90 in increments of 10. The unit of measure is milliseconds (ms).

Disables error control reporting.

Enables error control reporting.

Displays a list of valid +ER settings.

This is a compound parameter. The full syntax is as follows:

+ESA=<trans_idle>,<frame_idle>,<framed_un_ov>,

<hd_auto>,<crc_type>,<nrzi_en>,<syn1>

This modem does not use the <framed_un_ov>, <hd_auto>, and <syn1> parameters.

None.

+GCI=? displays a list of valid country codes.

off

Disables reporting of local port rate.

Enables reporting of local port rate.

Displays a list of valid +ILRR settings.

Displays a list of supported transmission rates.

The signal threshold, in octets, above which the DCE will generate a flow-off signal.

The signal threshold, in octets, below which the DCE will generate a flow-on signal.

Displays a list of valid +ITF settings.

Enables modulation reporting.

The DCE transmits the +MRR:<rate>,<rx_rate>, and the +MCR:<carrier> intermediate result codes to the DTE.

The <carrier> reported is the current modulation; the <rate> is the transmit rate in bps or is zero if negotiation fails; the <rx_rate> is the receive channel rate and is only reported when different receive and transmit rates have been negotiated.

Disables modulation reporting.

Displays a list of valid +MR settings.

This is a compound parameter. The full syntax is as follows:

+MS=<carrier>,<automode>,<min_rate>,

<max_rate>,<min_rx_rate>,<max_rx_rate>

Displays a list of valid +MS settings.

Note that this command is functionally the same as the #CID command.

Disables Caller ID.

Enables formatted Caller ID.

Enables unformatted Caller ID.

Displays a list of valid #CID settings.

S-Registers

To change a setting, use the ATSr=n command, where r is the register number and n is a decimal value from 0 to 255 (unless otherwise indicated).

Example: ATS7=120 sets the time that the modem will wait for a connection from your carrier to 120 seconds.

To view a setting, use the ATSr? command, where r is the register number.

Note: These S-Register values are the default settings for North America. Your default settings may be different if you live outside North America.

Register

S10

S11

S12

S18

S21

S22

S23

S24

S28

S30

S36

S37

S38

S48

Default

119

Function

Sets number of rings on which to answer in Auto Answer mode. When set to 0, Auto Answer is disabled.

Counts and stores number of rings from an incoming call. (S0 must be greater than 0.)

Stores ASCII decimal code for the escape code character. Default character is +. A value of 128–255 disables escape code.

Stores ASCII code for the Carriage Return character. Valid range is 0–127.

Stores ASCII decimal code for the Line Feed character. Valid range is 0–127.

Stores ASCII decimal code for the Backspace character. A value of 128–255 disables Backspace key's delete function.

Sets number of seconds modem waits before dialling. If Xn is set to X2 or X4, this is time-out length if no dial tone.

Sets number of seconds modem waits for a carrier. May be increased as needed, for example to allow modem time to establish an international connection.

Sets duration, in seconds, for pause (,) option in the Dial (Dn) command. Valid range is 0–32.

Sets required duration, in tenths of a second, of remote modem's carrier signal before recognition by your USRobotics modem.

Sets duration, in tenths of a second, that modem waits to hang up after loss of carrier. This guard time allows your modem to distinguish a line disturbance from a true disconnect (hang up) by the remote modem.

Note: If you set S10 = 255, the modem will not hang up when carrier is lost. Dropping DTR hangs up the modem.

Sets duration and spacing, in milliseconds, of dialled tones.

Sets duration, in fiftieths of a second, of guard time for escape code sequence (+++).

Test timer for &T loopback testing. Sets the time in seconds of testing before the modem automatically times out and terminates the test. When set to 0, the timer is disabled. Valid range is 1–255.

Sets length, in 10-millisecond units, of breaks sent from the modem to the computer; applies to MNP or V.42 mode only.

Stores ASCII decimal code for the XON character.

Stores ASCII decimal code for the XOFF character.

Sets duration, in seconds, for the sleep mode timer. The timer activates when there is no activity in the off-line command state. At timeout, the modem goes into standby mode. S24 = 0 disables the timer. Valid range is 0, 5–65.

Value

Result

Disables V.34 modulation.

Enables V.34 modulation.

Sets the duration, in minutes, for the inactivity timer. The timer activates when there is no data activity on the line; at timeout, the modem hangs up. S30=0 disables the timer. Valid range is 0–255.

Specifies the action to be taken in the event of negotiation failure when error control is selected.

Used in conjunction with S48, LAPM error control and feature negotiation to negotiate certain connection types.

Sets the maximum line data rate. In V.90 mode, sets the upstream V.34 rate.

Once a connection type (V.90) is determined, forces a particular downstream rate. A value of zero disables both connection types and allows a more reliable V.34 connection. The default value of 1 lets the modem select the downstream rate automatically. Other values force the downstream rate, with fallback to V.34 if unsuccessful at the configured rate.

Enables or disables error control and feature negotiation. Works in conjunction with S36 to determine the type of error correction method to use.

Value

128

Result

Enables negotiation.

Disables negotiation.

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