Technical Reference

Using Commands

Basic Data Commands

Command Function Options
<control key>S Stop or restart help screens. None.

<control key>C
or
<control key>K

 Stop help screens. None.
$ Use in conjunction with D, S, or & commands (or just AT) to display a basic command list; online help. None.
A Manual Answer : Goes off hook in answer mode. Pressing any key before connected aborts the operation. None.
A/ Re-executes the last issued command. Used mainly to redial. Does not require the AT prefix or a Carriage Return. 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.
+++ Escapes to online-command mode. None.
Any key Aborts off hook dial/answer operation and hangs up. None.
AT Required command prefix, except with A/, +++, and A>. Use alone to test for OK result code. None.
Bn U.S./ITU-T answer sequence B0 ITU-T answer sequence.
B1 U.S. answer tone.
Dn Dials the specified phone number. 0 - 9
Numeric digits.
#, * Extended touch-tone pad tones.
L Dials the last dialed number.
P Pulse (rotary) dial.
R Originates call using answer (reverse) frequencies.
Sn Dials the phone number string stored in NVRAM at position n (n = 0 - 3). Phone numbers are stored with the &Zn=s command.
T Tone dial
, (Comma) Pause. Linked to S8 register.
; (Semicolon) Return to Command mode after dialing.
" Dials the letters that follow (in an alphabetical phone number).
! (Exclamation point) Flashes the switch hook.
/ Delays for 125 ms. before proceeding with dial string.
W Wait for second dial tone (X2 or X4); linked to S6 register.
@ Dials, waits for quiet answer, and continues (X3 or higher).
$ Displays a list of Dial commands.
En Sets local echo. E0 Echo OFF.
E1 Modem displays keyboard commands.
Fn Sets online local echo of transmitted data ON/OFF. F0 Local echo ON. Modem sends a copy of the data it sends to the remote system to your screen.
F1 Local echo OFF. Receiving system may send a remote echo of data it receives.
Hn Controls ON/OFF hook. H0 Hangs up (goes on hook).
H1 Goes off hook.
In Displays the following information. I0 Four-digit product code.
I1 Results of ROM checksum.
I2 Results of RAM checksum.
I3 Product type.
I4 Current modem settings.
I5 Nonvolatile memory (NVRAM) settings.
I6 Link diagnostics.
I7 Product configuration.
I9 Plug and Play information.
I11 Extended link diagnostics.
Ln Controls speaker volume L0 Low volume.
L1 Low volume.
L2 Medium volume.
L3 High volume.
Mn Operates speaker M0 Speaker always OFF.
M1 Speaker ON until CONNECT.
M2 Speaker always ON.
M3 Speaker ON after dial, until CONNECT.
On Returns online. O0 Returns online.
O1 Returns online and retrains.
P Sets pulse dial (for phone lines that don't support touch-tone dialing). &P0 Pulse Dialing Disabled.
&P1 Canada, Denmark, Germany, Austria, Finland, Switzerland, Netherlands, Italy, United States, South Africa, Czech Republic.
&P2 France, United Kingdom, Belgium, Ireland, Spain, Portugal, Australia, Asia, Korea.
&P3 Norway.
&P4 New Zealand.
&P5 Japan.
&P6 Sweden.
Qn Displays/suppresses result codes. Q0 Displays result codes.
Q1 Quiet mode; no result codes.
Sr=n Sets register r to n. None.
Sr? Displays contents of S-Register r. None.
S$ Displays a list of the S-Registers. None.
T Sets tone dial. None.
Vn Displays verbal/numeric result codes. V0 Numeric codes.
V1 Verbal codes.
Xn Sets result code displayed. Default is X4.

Complete List of Result Codes

Result Codes X0 X1 X2 X3 X4
0/OK * * * * *
1/CONNECT * * * * *
2/RING * * * * *
3/NO CARRIER * * * * *
4/ERROR * * * * *
5/CONNECT 1200   * * * *
6/NO DIAL TONE     *   *
7/BUSY       * *
8/NO ANSWER       * *
9/Reserved          
10/CONNECT 2400   * * * *
13/CONNECT 9600   * * * *
18/CONNECT 4800   * * * *
20/CONNECT 7200   * * * *
21/CONNECT 12000   * * * *
25/CONNECT 14400   * * * *
43/CONNECT 16800   * * * *
85/CONNECT 19200   * * * *
91/CONNECT 21600   * * * *
99/CONNECT 24000   * * * *
103/CONNECT 26400   * * * *
107/CONNECT 28800   * * * *
151/CONNECT 31200   * * * *
155/CONNECT 33600   * * * *
256/CONNECT 28000   * * * *
260/CONNECT 29333   * * * *
264/CONNECT 30666   * * * *
268/CONNECT 32000   * * * *
180/CONNECT 33333   * * * *
272/CONNECT 34666   * * * *
276/CONNECT 36000   * * * *
184/CONNECT 37333   * * * *
280/CONNECT 38666   * * * *
284/CONNECT 40000   * * * *
188/CONNECT 41333   * * * *
192/CONNECT 42666   * * * *
196/CONNECT 44000   * * * *
200/CONNECT 45333   * * * *
204/CONNECT 46666   * * * *
208/CONNECT 48000   * * * *
212/CONNECT 49333   * * * *
216/CONNECT 50666   * * * *
220/CONNECT 52000   * * * *
224/CONNECT 53333   * * * *
228/CONNECT 54666   * * * *
232/CONNECT 56000   * * * *
Adaptive Dialing     * * *
Wait for 2nd Dial Tone (W)     *   *
Wait for Answer (@)       * *
Fast Dial     *   *

 *Requires @ in dial string; replaces NO CARRIER.
Yn Selects power-on/reset default configuration. Y0 Use profile 0 setting in NVRAM.
Y1 Use profile 1 setting in NVRAM.
Y2 Use factory configuration 0.
Y3 Use factory configuration 1.
Y4 Use factory configuration 2
Z Resets modem. Z0 Resets modem to NVRAM profile selected by Y command or dip 7.
Z1 Resets modem to NVRAM profile 0.
Z2 Resets modem to NVRAM profile 1.
Z3 Resets modem to factory default profile 0 (&F0).
Z4 Resets modem to factory default profile 1 (&F1).
Z5 Resets modem to factory default profile 2 (&F2).

Extended Data Commands

Command Function Options
&$ Displays a list of ampersand (&) commands. None.
&An Enables/disables added result code subsets (see Xn). &A0 ARQ result codes disabled.
&A1 ARQ result codes enabled.
&A2 V.XX modulation indicator added.
&A3 Protocol indicators added LAPM/MNP/NONE (error control) and V42bis/MNP5 (data compression).
&Bn Manages modem's serial port rate. &B0 Variable, follows connection rate.
&B1 Fixed serial port rate.
&B2 Fixed in ARQ mode, variable in non-ARQ mode.
&Cn Controls Carrier Detect (CD) signal. &C0 CD override.
&C1 Normal CD operations.
&Dn Controls Data Terminal Ready (DTR) operations. &D0 DTR override.
&D1 DTR toggle causes online Command mode.
&D2 Normal DTR operations.
&D3 Resets on receipt of DTR.
&Fn Loads a read-only (non-programmable) factory configuration. &F0 No flow control template.
&F1 Hardware flow control template.
&F2 Software flow control template.
&Gn Sets Guard Tone. &G0 No guard tone, U.S. and Canada.
&G1 550 Hz guard tone, some European countries, requires B0 setting.
&G2 1800 Hz guard tone, U.K., requires B0 setting.
&Hn Sets Transmit Data (TD) flow control (see also &Rn). &H0 Flow control disabled.
&H1 Hardware flow control, Clear to Send (CTS).
&H2 Software flow control, XON/XOFF.
&H3 Hardware and software flow control.
&In Sets Receive Data (RD) software flow control (see also &Rn). &I0 Software flow control disabled.
&I1 XON/XOFF signals to your modem and remote system.
&I2 XON/XOFF signals to your modem only.
&Kn Enables/disables data compression. &K0 Data compression disabled.
&K1 Auto enable/disable.
&K3 MNP5 compression disabled.
&Mn Sets Error Control (ARQ) for connections at 1200 bps and higher. &M0 Normal mode, error control disabled.
&M1 Reserved.
&M2 Reserved.
&M3 Reserved.
&M4 Normal/ARQ.
&M5 ARQ mode.
&Nn Sets connect speed. If connection cannot be made at this speed, the modem will hang up.

When used in conjunction with &Un, and &Un is greater than 0, &Nn sets the ceiling connect speed. &Un sets the floor connect speed.

 &N0 Connection speed is determined by the remote modem.
&N1 300 bps.
&N2 1200 bps.
&N3 2400 bps.
&N4 4800 bps.
&N5 7200 bps.
&N6 9600 bps.
&N7 12,000 bps.
&N8 14,400 bps.
&N9 16,800 bps.
&N10 19,200 bps.
&N11 21,600 bps.
&N12 24,000 bps.
&N13 26,400 bps.
&N14 28,800 bps.
&N15 31,200 bps.
&N16 33,600 bps.
&N17 28,000 bps.
&N18 29,333 bps.
&N19 30,666 bps.
&N20 32,000 bps.
&N21 33,333 bps.
&N22 34,666 bps.
&N23 36,000 bps.
&N24 37,333 bps.
&N25 38,666 bps.
&N26 40,000 bps.
&N27 41,333 bps.
&N28 42,666 bps.
&N29 44,000 bps.
&N30 45,333 bps.
&N31 46,666 bps.
&N32 48,000 bps.
&N33 49,333 bps.
&N34 50,666 bps.
&N35 52,000 bps.
&N36 53,333 bps.
&N37 54,666 bps.
&Pn Sets pulse (rotary) dial make/break ratio. &P0 Pulse Dialing Disabled.
&P1 Canada, Denmark, Germany, Austria, Finland, Switzerland, Netherlands, Italy, United States, South Africa, Czech Republic.
&P2 France, United Kingdom, Belgium, Ireland, Spain, Portugal, Australia, Asia, Korea.
&P3 Norway.
&P4 New Zealand.
&P5 Japan.
&P6 Sweden.
&Rn Sets Receive Data (RD) hardware flow control, Request to Send (RTS) (see also &Hn). &R0 Reserved.
&R1 Modem ignores RTS.
&R2 Received Data to computer only on RTS.
&Sn Controls Data Set Ready (DSR) operations. &S0 DSR override; always ON.
&S1 Modem controls DSR.
&Tn Begins test modes. &T0 Ends testing.
&T1 Analog Loopback.
&T2 Reserved.
&T3 Local Digital Loopback.
&T8 Analog Loopback with self-test and error detector.
&Un With n > 0, sets the floor connect speed (lowest acceptable connection speed).

Note: If your modem cannot connect to the remote modem at or above the speed set with this command, it will hang up.

 &N=0 & U=0 Connects at highest available speed. This default setting should be sufficient for most users.
&N>0 Connects at fixed speed.
&U>0 Connects at highest speed above &Un.
&N>0 &U>0 Connects at highest speed between &Nn and &Un.
&U0 No minimum connection speed.
&U1 300 bps.
&U2 1200 bps.
&U3 2400 bps.
&U4 4800 bps.
&U5 7200 bps.
&U6 9600 bps.
&U7 12,000 bps.
&U8 14,400 bps.
&U9 16,800 bps.
&U10 19,200 bps.
&U11 21,600 bps.
&U12 24,000 bps.
&U13 26,400 bps.
&U14 28,800 bps.
&U15 31,200 bps.
&U16 33,600 bps.
&U17 28,000 bps.
&U18 29,333 bps.
&U19 30,666 bps.
&U20 32,000 bps.
&U21 33,333 bps.
&U22 34,666 bps.
&U23 36,000 bps.
&U24 37,333 bps.
&U25 38,666 bps.
&U26 40,000 bps.
&U27 41,333 bps.
&U28 42,666 bps.
&U29 44,000 bps.
&U30 45,333 bps.
&U31 46,666 bps.
&U32 48,000 bps.
&U33 49,333 bps.
&U34 50,666 bps.
&U35 52,000 bps.
&U36 53,333 bps.
&U37 54,666 bps.
&Wn Writes current configuration to NVRAM templates. &W0 Modifies the NVRAM 0 template (Y0).
&W1 Modifies the NVRAM 1 template (Y1).
&Yn Sets break handling. &Y0 Destructive, but doesn't send break.
&Y1 Destructive, expedited.
&Y2 Nondestructive, expedited.
&Y3 Nondestructive, unexpedited.
&Zn=s Writes phone number string s to NVRAM at position n (n = 0 - 3). None.
&Zn=L Writes last executed dial string to NVRAM at position n (n = 0 - 3). None.
&Zn? Displays phone number stored at position n (n = 0 - 3). None.
&ZL? Displays the last executed dial string. None.

S Registers

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

Register Default Function
S0 0 Sets number of rings on which to answer in Auto Answer mode. When set to 0, Auto Answer is disabled.
S1 0 Counts and stores number of rings from an incoming call. (S0 must be greater than 0.)
S2 43 Stores ASCII decimal code for the escape code character. Default character is +. A value of 128–255 disables escape code.
S3 13 Stores ASCII code for the Carriage Return character. Valid range is 0–127.
S4 10 Stores ASCII decimal code for the Line Feed character. Valid range is 0–127.
S5 8 Stores ASCII decimal code for the Backspace character. A value of 128–255 disables Backspace key's delete function.
S6 4 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.
S7 60 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.
S8 2 Sets duration, in seconds, for pause (,) option in the Dial (Dn) command. Valid range is 0–32.
S9 6 Sets required duration, in tenths of a second, of remote modem's carrier signal before recognition by your USRobotics modem.
S10 14 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.

If you set S10 = 255, the modem will not hang up when carrier is lost. Dropping DTR hangs up the modem.
S11 73 Sets duration and spacing, in milliseconds, for tone dialling.
S12 50 Sets duration, in fiftieths of a second, of guard time for escape code sequence (+++).
S13 0 Bit-mapped register. Select the bit(s) that you want on and set S13 to the sum of their values in the "Value" column.

For example, to enable bits 0 and 4, first add the corresponding Values (1 and 16,) then set the register to the sum (17) as follows: ATS13=17

Bit Value Result
0 1 Reset when DTR drops.
1 2 Reserved.
2 4 Set backspace key to delete.
3 8 On DTR signal, auto-dial the number stored in NVRAM at position 0.
4 16 At power on/reset, auto-dial the number stored in NVRAM at position 0.
5 32 Reserved.
6 64 Disable quick retrains.
7 128 Disconnect on escape code.
S14 0 Reserved.
S15 0 Bit-mapped register. Select the bit(s) that you want on and set S15 to the sum of their values in the "Value" column.

For example, to enable bits 0 and 4, first add the corresponding Values (1 and 16,) then set the register to the sum (17) as follows: ATS15=17

Bit Value Result
0 1 Reserved.
1 2 Reserved.
2 4 Reserved.
3 8 Reserved.
4 16 Disable MNP level 4.
5 32 Disable MNP level 3.
6 64 MNP incompatibility.
7 128 Disable V.42 operation.
S16 0 Reserved.
S17 0 Reserved.
S18 0 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.
S19 0 Sets duration, in minutes, for inactivity timer. This timer activates when there is no data activity on the phone line; at time-out the modem hangs up. S19 = 0 disables the timer.
S20 0 Reserved.
S21 10 Sets length, in 10-millisecond units, of breaks sent from the modem to the computer; applies to MNP or V.42 mode only.
S22 17 Stores ASCII decimal code for the XON character.
S23 19 Stores ASCII decimal code for the XOFF character.
S24 0 Reserved.
S25 5 Sets duration, in hundredths of a second, of a true DTR drop. Prevents modem from interpreting random glitches as DTR loss.

Most users will use the default; this register is useful for compatibility with older systems and operating software.
S26 0 Reserved.
S27 0 Bit-mapped register. Select the bit(s) that you want on and set S27 to the sum of their values in the "Value" column.

For example, to enable bits 0 and 4, first add the corresponding Values (1 and 16,) then set the register to the sum (17) as follows: ATS27=17

Bit Value Result
0 1 Enables ITU-T V.21 modulation at 300 bps for overseas calls; in V.21 mode, the modem answers both overseas and domestic (U.S. and Canada) calls, but only originates V.21 calls (default Bell 103).
1 2 Reserved.
2 4 Disables V.32 modulation.
3 8 Reserved.
4 16 Enables V.23 fallback mode.
5 32 Disables V.32bis mode.
6 64 Disable V.42 selective reject.
7 128 Software compatibility mode. This setting disables the codes and displays the 9600 code instead. The actual rate of the call can be viewed on the ATI6 screen. Used for unusual software incompatibilities. Some software may not accept 7200, 12,000, and 14,400 bps or greater result codes.
S28 8 0 Eliminates the V.32 answer tones for a faster connection.
8 Default item, all times are in tenths of seconds.
255 Disables all connections except V.32 at 9600 bps.
S29 20 Reserved.
S30 0 Reserved.
S31 128 Reserved.
S32 2 Bit-mapped register. Select the bit(s) that you want on and set S32 to the sum of their values in the "Value" column.

For example, to enable bits 0 and 4, first add the corresponding Values (1 and 16,) then set the register to the sum (17) as follows: ATS32=17

Bit Value Result
0 1 V.8 Call Indicate enabled.
1 2 Enables V.8 mode.
2 4 Reserved.
3 8 Disables V.34, V.90, and V.92 modulation.
4 16 Disables V.34+ modulation.
5 32 Reserved.
6 64 Disables V.90 modulation.
7 128 Reserved.
S33 0 Bit-mapped register. Select the bit(s) that you want on and set S33 to the sum of their values in the "Value" column.

For example, to enable bits 0 and 4, first add the corresponding Values (1 and 16,) then set the register to the sum (17) as follows: ATS33=17

Bit Value Result
0 1 Disables 2400 symbol rate.
1 2 Disables 2743 symbol rate.
2 4 Disables 2800 symbol rate.
3 8 Disables 3000 symbol rate.
4 16 Disables 3200 symbol rate.
5 32 Disables 3429 symbol rate.
6 64 Reserved.
7 128 Reserved.
S34–S37 Reserved. Reserved.
S38 0 Sets an optional delay, in seconds, before a forced hang-up and clearing of the Transmit buffer when DTR drops during an ARQ call. This allows time for a remote modem to acknowledge receipt of all transmitted data before it is disconnected. The modem immediately hangs up when DTR drops.

This option only applies to connections terminated by dropping DTR. If the modem receives the ATH command, it ignores S38 and immediately hangs up.
S39-S40 Reserved. Reserved.
S41 0

Bit-mapped register setup. To set registers, see instructions for S13.

Bit Value Result
0 1 Enable Distinctive Ring.
1 2 Reserved.
2 4 Reserved.
3 8 Enable v.44 compression.
4 16 Reserved.
5 32 Reserved.
6 64 Reserved.
7 128 Enable v.22 FastConnect.
S42 Reserved. Reserved.