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.

CommandFunctionDefaultOptions
+++Escapes to online-command mode. Does not require the ATprefix or a carriage return.None.None.
$Displays help for basic commands.None.None.
AManual Answer. Goes off hook in answer mode. Pressing any key before the connection is complete aborts the operation.None.None.
A/Re-executes the last issued command. Used mainly to redial. Does not require the AT prefix or a carriage return.None.None.
A>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.None.None.
BnSet handshaking options.B1 when the modem is at 1200 bps.

B16 when the modem is at 300 bps.
B0Selects CCITT V.22 mode when the modem is a 1200 bps.
B1Selects Bell 212A when the modem is at 1200 bps. Use only if the modem is not required to answer V.34-type calls.
B2, B3Deselects V.23 reverse channel.
B15Selects V.21 when the modem is at 300 bps.
B16Selects Bell 103J when the modem is at 300 bps.
DnDials 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).None.The maximum length of a dial string is 60 characters.
D0–D9Numeric digits.
D#D*Extended touch-tone pad tones.
DLDials the last phone number dialled.
DL?Displays last phone number dialled.
DPPulse (rotary) dial.
DTTone (DTMF) dial
DWWaits for second dial tone (X2 or X4); linked to S6 register.
D!(Exclamation point) Flashes the switch hook.
D,(Comma) Pauses. Linked to S8 register.
D/(Slash) Delays for 125 ms. before proceeding with dial string.
D;(Semicolon) Returns to Command mode after dialling.
D@Dials, waits for quiet answer, and continues (X3 or higher).
D"(Quotation mark) Dials with alphabetic letters between quotes converted to numbers.
D^(Circumflex) Disables data calling tone transmission.
DS=nDials the phone number string stored in NVRAM at position n. Phone numbers are stored with the &Zn=s command.None.0–2
EnSets local echo.E1E0Modem does not display keyboard commands.
E1Modem displays keyboard commands.
HControls hook functions.H0H0Modem goes on-hook.
H1Modem goes off-hook.
InDisplays the information associated with n.None.I0Four-digit product code.
I1Results of ROM checksum.
I2Results of RAM checksum.
I3Product type.
I4Current modem settings.
I5Nonvolatile memory (NVRAM) settings.
I6Link diagnostics.
I7Product configuration.
I9Plug and Play information.
I11Extended link diagnostics.
I92V.92 settings.
LnControls speaker volume.
Note:Modem does not have a speaker.
Command is included for compatibility.
L1L0Low.
L1Low.
L2Medium.
L3High.
MnOperates speaker.M1M0Speaker always OFF.
M1Speaker ON until CONNECT.
M2Speaker always ON.
M3Speaker ON after dial, until CONNECT.
NControls modulation handshakeN10When originating or answering, this is for handshake only at the communication standard specified by register S37 and the B<value> command.
1When 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.
OnReturns online.None.O0Returns online from command mode.
O1Returns online and retrains.
PSets pulse dialling (rotary dialling).None.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.
QnDisplays/suppresses result codes.Q0Q0Displays result codes.
Q1Quiet mode; does not display result codes.
Sr=nSets S-register r to the value n. For register values, see S-Registers.None.None.
TSets DTMF tone dialling.None.None.The modem uses tone dialling by default.
VnDisplays verbal/numeric result codes.V1V0Displays numeric result codes.
V1Displays verbal result codes.
WnEnables tone detection options.W2W0CONNECT result code reports DTE receive speed. Disables protocol result codes.
W1CONNECT result code reports DTE receive speed. Enables protocol result codes.
W2CONNECT result code reports DCE receive speed. Enables protocol result codes.
XnSets result codes displayed.X4This 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. 

Commands
CommandExtended Result CodesDial Tone DetectBusy Tone Detect
X0DisabledDisabledDisabled
X1EnabledDisabledDisabled
X2EnabledEnabledDisabled
X3EnabledDisabledEnabled
X4EnabledEnabledEnabled
X5, X6EnabledEnabledEnabled
X7DisabledEnabledEnabled

Option Description
FunctionEnabledDisabled
Ext Result CodesDisplays basic result codes, connect messages with data rate, and an indication of the modem's error correction and data compression operations.Displays the basic result codes.
Dial Tone DetectDials upon detection of a dial tone and disconnects the call if the dial tone is not detected within 10 seconds.Dials a call regardless of whether the modem detects a dial tone. Register S6 contains the dial delay.
Busy Tone DetectMonitors for busy tones.Ignores all busy tones.

Option Result Codes
CommandResult Codes
X0• OK• Ring• Error
• Connect• No Carrier 
X1• OK• Ring• Error
• Connect <Rate>• No Carrier 
X2• OK• Ring• Error
• Connect <Rate>• No Carrier• No dial tone
X3• OK• Ring• Error
• Connect <Rate>• No Carrier• Busy
• Blacklisted  
X4• OK• Ring• Error
• Connect <Rate>• No Carrier• Busy
• Blacklisted• Delayed• No dial tone
• Call Waiting detected  
X5, X6• OK• Ring• Error
• Connect <Rate>• No Carrier• Busy
• Blacklisted• Delayed• No dial tone
• Call Waiting detected  
X7• OK• Ring• Error
• Connect• No Carrier 
YnSelects reset default configuration.Y0Y0Selects stored profile (&W).
Y1Selects stored profile (&W).
Y2Selects factory configuration 0 (&F0).
Y3Selects factory configuration 1 (&F1).
Y4Selects factory configuration 2 (&F2).
ZnResets modem.Z0Z0Resets the modem to NVRAM profile selected by Y command.
Z1Resets the modem to the stored profile (&W).
Z2Resets the modem to the stored profile (&W).
Z3Resets the modem to factory default profile 0 (&F0).
Z4Resets the modem to factory default profile 1 (&F1).
Z5Resets the modem to factory default profile 2 (&F2).
#CID=nControls Caller ID.None.#CID=0Disables Caller ID.
#CID=1Enables formatted Caller ID.
#CID=2Enables unformatted Caller ID.
#UDDisplays Unimodem Diagnostics.None.None.
%BDisplays numbers in blacklist. (Country selection must support blacklist.)None.None.
%EnControls Fallback/Fallforward.%E2%E0Fallback/Fallforward disabled.
%E1Fallback enabled, Fallforward disabled.
%E2Fallback/Fallforward enabled.
&AnEnables/disables added result code subsets (see Xn).&A3&A0ARQ result codes disabled.
&A1ARQ result codes enabled.
&A2V.xx modulation indicator added.
&A3Protocol indicators added: LAPM/MNP/NONE (error control) and V42bis/MNP5 (data compression).
&BnManages the modem's serial port rate.&B1&B0Serial DTE rate is variable, follows connection rate.
&B1Fixed DTE rate.
&CnControls Carrier Detect (CD) signal.&C1&C0CD override.
&C1Normal CD operation.
&DnControls Data Terminal Ready (DTR) operations.&D2&D0Data Terminal Ready (DTR) override.
&D1DTR toggle causes online Command mode.
&D2Normal DTR operation.
&D3Resets on receipt of DTR.
&FnResets the modem and loads a read-only (non-programmable) factory configuration.None.&F0Loads a generic template.
&F1Loads the hardware flow control template.
&F2Loads the software flow control template.
&GnSets Guard Tone.&G0&G0No guard tone, U.S. and Canada.
&G1550 Hz guard tone; requires B0 setting.
&G21800 Hz guard tone; requires B0 setting.
&HnSets Transmit Data (TD) flow control.&H1&H0Flow control disabled.
&H1Hardware flow control, Clear to Send (CTS).
&H2Software flow control, XON/XOFF.
&KnEnables/disables data compression.&K1&K0Data compression disabled.
&K1Auto enable/disable.
&MnSets Error Control (ARQ) for connections at 1200 bps and higher.&M4&M0Normal mode, error control disabled.
&M4Auto Normal/ARQ.
&M5ARQ required for connection.
&NnSets S registers to attempt forced speed.&N0
nRateS28S37S38
0Auto rate101
1300 V.21/B103030
21200 V.22050
32400 V.22bis060
44800 V.32070
57200 V.32080
69600 V.32090
712000 V.32bis0100
814400 V.32bis0110
916800 V.32ter0120
1019200 V.32ter0130
1121600 V.341140
1224000 V.341150
1326400 V.341160
1428800 V.341170
1531200 V.34+1180
1633600 V.34+1190
1728000 V.90102
1829333 V.90103
1930666 V.90104
2032000 V.90105
2133333 V.90106
2234666 V.90107
2337333 V.90108
2437333 V.90109
2538666 V.901010
2640000 V.901011
2741333 V.901012
2842666 V.901013
2944000 V.901014
3045333 V.901015
3146666 V.901016
3248000 V.901017
3349333 V.901018
3450666 V.901019
3552000 V.901020
3653333 V.901021
3754666 V.901022
3856000 V.901023
&PnSets the make-to-break ratio.&P1&P0U.S. ratio: 39%–61% at 10 pulses per second
&P1UK ratio: 39%–61% at 10 pulses per second
&P2UK ratio: 39%–61% at 20 pulses per second (Japan)
&SnSets the Data Set Ready (DSR) option.&S0&S0DSR override. DSR is always on.
&S1DSR comes on after establishing a connection and goes off when the connection ends.
&TnSets test modes.None.&T0Ends testing.
&T1Local Analogue Loopback (LAL).
&T3Local Digital Loopback (LDL).
&WnStores current configuration in NVRAM template.None.&W0
&YnSets break handling.&Y1&Y0Destructive, but doesn't send break.
&Y1Destructive, expedited.
&Y2Nondestructive, expedited.
&Y3Nondestructive, unexpedited.
&Zn=sStores phone number string s in NVRAM at position n.None.0–2Example: AT&Z1=18005551212 stores the phone number 18005551212 in position 1. Use the DS=n command to recall and dial the number.
\AnSelects maximum MNP block size.\A3\A064 characters.
\A1128 characters.
\A2192 characters.
\A3256 characters.
\BnSends break.\B31–9Expressed in hundreds of milliseconds.
\GnSets modem port flow control.\G0\G0The modem processes XON/XOFF flow control characters locally.
\G1The modem passes XON/XOFF flow control characters.
\XSets XON/XOFF pass through.\X0\X0The modem processes XON/XOFF flow control characters locally.
\X1The modem passes XON/XOFF flow control characters.
+A8E=nSets V.8 operation.+A8E=1,1,C1,1This is a compound parameter. The full syntax is as follows:

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

Valid values for <v8o>
ValueMeaning
1Enables DCE-controlled V.8 origination negotiation.
6Enables DCE-controlled V.8 origination negotiation, issue +A8x indications.

Valid values for <v8a>
ValueMeaning
1Enable DCE-controlled V.8 answer negotiation.
5Disable DCE-controlled V.8 answer negotiation, issue +A8x indications.

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

Valid values for <v8b>
ValueMeaning
0Disable V.8 negotiation.
1Enable DCE-controlled V.8bis negotiation.
2Enable DTE-controlled V.8 negotiation.
?Displays a list of valid +A8E settings.
+A8E?Display the current settings for V.8 or V.8 bis negotiation.None.None.
+A8T=nSends a V.8 bis signal or message from the local DCE when V.80 is enabledNone.This is a compound parameter. The full syntax is as follows:

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

Valid values for <signal>
ValueMeaning
0None.
1Initiating Mre.
2Initiating MRd.
3Initiating CRe, low power.
4Initiating CRe, high power.
5Initiating CRd.
6Initiating Esi.
7Responding MRd, low power.
8Responding MRd, high power.
9Responding CRd.
10Responding Esr.

Valid values for <sig_en>
ValueMeaning
0Enable detection of initiation signals (default).
1Enable detection of responding signals .

Valid values for <msg_en>
ValueMeaning
0Enable detection of messages (default).
1Enable detection of V.8 bis messages.

Valid values for <supp_delay>
ValueMeaning
0No delay inserted (default).
1Insert 1.5 second delay between transmitted V.8 bis signal and the subsequent V.8 bis message.
?Displays a list of valid +A8T settings.
+A8T?Displays the current +A8T setting.None.None.
+DCS=nSelects the data compression algorithm.+DCS=1,1This is a compound parameter. The full syntax is as follows:

+DCS=<v42bis>,<v44>

Valid values for <v42bis>
ValueMeaning
0Disable V.42bis.
1Enable V.42bis.

Valid values for <v44>
ValueMeaning
0Disable V.44.
1Enable V.44.
2Enable V.44 for V.92 servers only.
+DR=nControls data compression reporting.None.0Disables the compression report.
1Enables the compression report.
?Displays a list of valid +DR settings.
+DS=nConfigures the V.42 bis data compression method.+DS=3,0,1024,32This is a compound parameter. The full syntax is as follows:

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

Valid values for <direction>
ValueMeaning
0Does not negotiate V.42 compression.
3Negotiates V.42 compression in both directions.

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

ParameterFixed Value
compression_negotiation0
max_dict1024
max_string32
+DS44=nConfigures the V.44 data compression method.+DS44=3,0,0,1024,1024,
255,255,5120,4096
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>

Valid values for <direction>
ValueMeaning
0Does not negotiate V.44 compression.
3Negotiates V.44 compression in both directions.

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

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

Valid Values for Remaining Parameters
ParameterValid Values
max_codewords_tx256–2048
max_codewords_rx256–2048
max_string_tx31–255
max_string_4x31–255
max_history_tx512–11008
max_history_4x512–11008
+EB=nDetermines the action taken when a break is received.+EB=0,,30This is a compound parameter. The full syntax is as follows:

<break_selection>,<timed>,<default_length>

Valid Values for <break selection>
ValueMeaning
0Ignores break.
1Nonexpedited, nondestructive.
2Expedited, nondestructive.
3Expedited, destructive.
?Displays a list of valid +EB settings.

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).

+ER=nControls error control reporting.+ER=00Disables error control reporting.
1Enables error control reporting.
?Displays a list of valid +ER settings.
+ESASets up error control parameters.None.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.

Valid values for n
CombinationMode
0,,,,0,0,,Disables CRC generation and checking.
0,,,,1,0,,Causes the DCE to generate a 16-bit CRC in the transmit direction in framed sub-Mode and check the CRC in the receive direction.
+GCAPDisplays supported capabilities.None.None.
+GCI=nSets the country code.None.
CodeCountry CodeCountry
09Australia6CMalaysia
0AAustria73Mexico
0FBelgium7BNetherlands
20Canada7ENew Zealand
31Denmark82Norway
72Europe26People's Republic of China
3CFinland89Philippines
3DFrance8BPortugal
04 or 42Germany9CSingapore
46Greece9FSouth Africa
50Hong KongA0Spain
51HungaryA5Sweden
53IndiaA6Switzerland
54IndonesiaA9Thailand
57IrelandAETurkey
59ItalyB4United Kingdom
00JapanB5United States of America
61KoreaBCVietnam

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

+ILRR=nControls port rate reporting.+ILRR=00Disables reporting of local port rate.
1Enables reporting of local port rate.
?Displays a list of valid +ILRR settings.
+IPR=nDisplays DTE to DCE transmission rates.None.?Displays a list of supported transmission rates.
+ITF=nSets the transmit flow control thresholds.None.offThe signal threshold, in octets, above which the DCE will generate a flow-off signal.
onThe signal threshold, in octets, below which the DCE will generate a flow-on signal.
?Displays a list of valid +ITF settings.
+MR=nControls modulation reporting.None.0Enables 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.
1Disables modulation reporting.
?Displays a list of valid +MR settings.
+MS=nControls modulation.+MS=V92,1,31200,
56000,31200,56000
This is a compound parameter. The full syntax is as follows:

+MS=<carrier>,<automode>,<min_rate>,
<max_rate>,<min_rx_rate>,<max_rx_rate>

Valid <carrier> values
ValueMeaning
V92V.92
V90V.90
V34V.34
V32BV.32bis
V32V.32
V22BV.22bis
V22V.22
Bell212ABell 212A
V23CV.23, constant carrier, asymmetric FDM
V21V.21
Bell103Bell 103

Valid <automode> values
ValueMeaning
0Disables automatic modulation negotiation.

If a value is specified for <max_rate>, automatic rate selection is disabled and the modem will try to connect at the specified rate.

1Enables automatic modulation negotiation.

Valid <min_rate> range
ValueMeaning
31200Determined by modulation selected in <carrier>
300–56000Value limited by modulation selected in <carrier>.

Valid <min_rate> for each <carrier>
ValueMeaning
V342400–33600 bps in steps of 2400 bps.
V32bis4800–19200 bps in steps of 2400 bps.
V324800–14400 bps in steps of 2400 bps.
V22bis2400 bps.
V222200 bps.
V23C Bell212A1200 bps.
V.21, Bell103300 bps.

Valid <max_rate> range
ValueMeaning
56000Determined by modulation selected in <carrier>
300–56000Value limited by modulation selected in <carrier>.

Valid <max_rate> for each <carrier>
ValueMeaning
V9228000–56000 bps in steps of 1333 bps.
V9028000–56000 bps in steps of 1333 bps.
V342400–33600 bps in steps of 2400 bps.
V32bis4800–19200 bps in steps of 2400 bps.
V324800–14400 bps in steps of 2400 bps.
V22bis2400 bps.
V222200 bps.
V23C, Bell212A1200 bps.
V.21, Bell103300 bps.
?Displays a list of valid +MS settings.
+VCID=nControls Caller ID.+VCID=0Note that this command is functionally the same as the #CID command.
0Disables Caller ID.
1Enables formatted Caller ID.
2Enables 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 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 ATSrcommand, 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.

RegisterDefaultFunction
S00Sets number of rings on which to answer in Auto Answer mode. When set to 0, Auto Answer is disabled.
S10Counts and stores number of rings from an incoming call. (S0 must be greater than 0.)
S243Stores ASCII decimal code for the escape code character. Default character is +. A value of 128–255 disables escape code.
S313Stores ASCII code for the Carriage Return character. Valid range is 0–127.
S410Stores ASCII decimal code for the Line Feed character. Valid range is 0–127.
S58Stores ASCII decimal code for the Backspace character. A value of 128–255 disables Backspace key's delete function.
S64Sets number of seconds modem waits before dialling. If Xn is set to X2 or X4, this is time-out length if no dial tone.
S750Sets number of seconds modem waits for a carrier. May be increased as needed, for example to allow modem time to establish an international connection.
S82Sets duration, in seconds, for pause (,) option in the Dial (Dn) command. Valid range is 0–32.
S96Sets required duration, in tenths of a second, of remote modem's carrier signal before recognition by your USRobotics modem.
S1060Sets 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.
S1195Sets duration and spacing, in milliseconds, of dialled tones.
S1250Sets duration, in fiftieths of a second, of guard time for escape code sequence (+++).
S180Test 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.
S2152Sets length, in 10-millisecond units, of breaks sent from the modem to the computer; applies to MNP or V.42 mode only.
S22119Stores ASCII decimal code for the XON character.
S2355Stores ASCII decimal code for the XOFF character.
S2460Sets 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.
S281
ValueResult
0Disables V.34 modulation.
1Enables V.34 modulation.
S300Sets 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.
S367Specifies 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.

ValueResult if S48=7Result if S48=128
0 or 2V.42 or hang up(Do not use)
1 or 3V.42 or asynchronousAsynchronous
4 or 6V.42, MNP, or hang upMNP or hang up
5 or 7V.42, MNP, or asynchronousMNP or asynchronous
S370Sets the maximum line data rate. In V.90 mode, sets the upstream V.34 rate. 

ValueRateValueRate
0Auto rate1012000 bps
1Reserved1114400 bps
21200/75 bps (V.23)1216800 bps
3300 bps1319200 bps
4Reserved1421600 bps
512001524000 bps
62400 bps1626400 bps
748001728800 bps
872001831200 bps
996001933600 bps
S381Once 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. 

ValueRateValueRate
0V.90 disabled1241333 bps
1Auto rate1342666 bps
228000 bps1444000 bps
329333 bps1545333 bps
430666 bps1646666 bps
532000 bps1748000 bps
633333 bps1849333 bps
734666 bps1950666 bps
836000 bps2052000 bps
937333 bps2153333 bps
1038666 bps2254666 bps
1140000 bps2356000 bps
S48 Enables or disables error control and feature negotiation. Works in conjunction with S36 to determine the type of error correction method to use. 

ValueResult
7Enables negotiation.
128Disables negotiation.

 

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