Modem - Hayes AT-Commands - Functions

Modem - Hayes-AT - Commands - Functions

The Hayes-AT command set is not a definite standard, however most modems will follow near all of the below specified AT-commands.
If the origin Modem-Manual is available, I would highly recommend to use the origin setup instructions, rather than use the below tables.

When entering an AT-commandstring do not mix UPPER-CASE and lower-case letters.
(Sample: use AT&F -or- at&f and not aT&f )

Modem Commands - Functions

Command CMD-n Modem Function/Option
A   Manual Answer mode (when modem has not received
an incoming call) modem forced to Off Hook
A/   Re-execute last command once (Re-dial)
A>   Repeat last command (10x) continuously
  Any key Terminate current connection attempt,
and exit Repeat mode - go Off Hook
AT   Attention: must precede all other commands,
except A/, A>, and +++
Bn   U.S./(CCITT) ITU-T Handshake options
  B0 ITU-T-V.25 (CCITT) answer sequence
  B1 Reserved
Cn   Transmitter On/Off
  C0 Transmitter Off
  C1 Transmitter On-Default
Dn   Dial number n and go into originate mode
  P Pulse dial - Default
  T Touch-Tone dial (DTMF-tone)
  , (Comma) Pause for 2 seconds
  ; Return to AT-cmd state after dialing
  "... Dial the letters that follow
  ! Flash switch-hook to transfer call
  / (slash) Delayed (125ms) dial operation
  W Wait for 2nd dial tone (if X3 or higher is set)
  @ Wait for an answer (if X3 or higher is set)
  R Connect - use (Reverse) frequencies
  S Dial stored number
  DL Dial the last-dialed number
D$   Online Help - show dial commands
DSn   Dial number stored in NVRAM at position n (0-3)
En   Command mode local echo, not applicable after
a connection has been made
  E0 Echo Off
  E1 Echo On - Default
Fn   Local echo On/Off when a connection has been made
  F0 Echo On (Half duplex)
  F1 Echo Off (Full duplex) - Default
Hn   On/Off hook control
  H0 Hang up (go on hook) - Default
  H1 Go off hook
In   Inquiry
  I0 Return modem product code/version
  I1 Return memory (ROM) checksum
  I2 Run memory (RAM) test
  I3 Returns product-type or call duration/real time
  I4 Return current active modem settings
  I5 Return NVRAM settings
  I6 Return link diagnostics
  I7 Return product (Flash) configuration
  I9 Return Plug-and-Play (PnP) information
  I11 Return connection statistic
Kn   Modem clock operation
  K0 ATI3 displays call duration - Default
  K1 ATI3 displays real time, set with ATI3=HH:MM:
Ln   Loudness of speaker volume
  L0 Low
  L1 Low
  L2 Medium
  L3 High
Mn   Monitor (speaker) control
  M0 Speaker always set to Off
  M1 Speaker On until carrier is established - Default
  M2 Speaker always On
  M3 Speaker On after last digit dialed out,
Off at start (connect) carrier detected
On   Return on-line after command execution
  O0 Return on-line, normal
  O1 Return on-line, start retrain
P   Pulse dial
Qn   Result codes display
  Q0 Result codes displayed
  Q1 Result codes suppressed (quiet mode)
  Q2 Result codes during dial out only
  Q3 Result codes only in answering mode
Sr=n   Set Register commands: r is any S-register,
n must be a decimal number between 0 and 255.
Sr.b=n   Set bit.b of register r to n (0=OFF or 1=On)
Sn?   Query register n
T   Tone dial
Vn   Verbal/Numeric result codes
  V0 show numeric result codes
  V1 show verbal (text) result codes
Xn   Result code options - Default = X4
Yn   Load working RAM at PWR-On/reset with
configuration (data) from
  Y0 Load NVRAM-profile 0 - Factory default 0
  Y1 Load NVRAM-profile 0 - Factory default 1
  Y2 Load user profile - &F0
  Y3 Hardware profile - Factory &F1
  Y4 Software profile - Factory &F2
Zn   Modem - reset control
  Z0 Reset Modem - use Y-command NVRAM profile
  Z1 Reset Modem - use NVRAM Profile-0
  Z2 Reset Modem - use NVRAM Profile-1
  Z3 Reset Modem - use Factory Profile-0
  Z4 Reset Modem - use Factory Profile-1
  Z5 Reset Modem - use Factory Profile-2
+++   Escape code sequence, preceded and followed by at
least one second of no data transmission.
>   Repeat command continuosly or up to 10 dial
attempts Canceled by pressing any key
$   Online Help - Basic command summary
&$   Online Help - & command summary
%$   Online Help - % command summary
D$   Online Help - Dial command summary
S$   Online Help - S-Register summary
<Ctrl>S   Stop/restart display of HELP screens
<Ctrl>C   Cancel display of HELP screens
<Ctrl>K   Cancel display of HELP screens
&An   ARQ result codes 14-17, 19
  &A0 Supress ARQ result codes
  &A1 Display ARQ result codes
  &A2 Display HST and V.32 result codes
  &A3 Display protocol result codes LAMP/MNP/NONE
- Default
&Bn   Data Rate, terminal-to-modem (DTE/DCE)
  &B0 DTE rate follows connection rate - Default
  &B1 Fixed DTE rate - Default
  &B2 Fixed DTE rate in ARQ mode, variable DTE rate
in non-ARQ mode.
&Cn   Carrier Detect (CD) operations
  &C0 CD override
  &C1 Normal CD operations - Default
&Dn   Data Terminal Ready (DTR) operations
  &D0 DTR override
  &D1 Reserved
  &D2 Normal DTR Operation - Default
&Fn   Load Factory default settings into working RAM
  &F0 Load user (saved) settings into working RAM
  &F1 Load hardware-control profile
  &F2 Load software-control profile
&Gn   Guard tone
  &G0 No guard tone, U.S. and Canada - Default
  &G1 550Hz-Guard tone, some European countries
  &G2 1800Hz-Guard tone, U.K. requires B0-setting
&Hn   Transmit Data flow control
  &H0 Flow control disabled - Default
  &H1 Hardware (CTS) flow control
  &H2 Software (XON/XOFF) flow control - Printer
  &H3 Hardware and software control
&In   Received Data software flow control
  &I0 Flow control disabled - Default
  &I1 XON/XOFF to local modem and remote computer
  &I2 XON/XOFF to local modem only
  &I3 Host mode, Hewlett Packard protocol
  &I4 Terminal mode, Hewlett Packard protocol
  &I5 ARQ mode same as &I2, non-ARQ mode,
look for incoming XON/XOFF
&Jn   Telephone jack selection
  &J0 RJ-11, RJ-41S, RJ-45S
  &J1 RJ-1, RJ-12, RJ-13
&Kn   Data Compression
  &K0 Disabled
  &K1 Auto enable/disable - Default
  &K2 Compression enabled
  &K3 MNP5 - compression disabled
&Ln   Switched/Leased line operation
  &L0 Normal phone line (switched) - Default
  &L1 Leased line
&Mn   Error Control/Synchronous Options => 1200 Bps
  &M0 Normal mode, no error (ARQ) control
  &M1 Synchronous mode
  &M2 Synchronous mode 2 stored number dialing
  &M3 Synchronous mode 2 manual dialing
  &M4 Normal/ARQ - Default
  &M5 ARQ mode hang-up if ARQ connection cannot be made
&Nn   Data Rate, data link (DCE/DCE)
  &N0 Variabl Rate operations - Default
  &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
&Pn   Pulse dial make/break ratio
  &P0 North America 39%-61% - Default
  &P1 British Commonwealth 33%-67%
&Rn   Received Data hardware (RTS) flow control
  &R0 CTS follow RTS
  &R1 Ignore RTS
  &R2 Pass received data on RTS high, used Pass received
data on RTS high - Default
&Sn   Data Set Ready (DSR) override
  &S0 DSR override (always on) - Default
  &S1 Modem controls DSR
&Tn   Modem Testing
  &T0 End Testing
  &T1 Analog loopback (AL-Test)
  &T2 Reserved
  &T3 Digital loopback (DL-Test)
  &T4 Grant remote digital loopback (RDL-Test)
  &T5 Deny remote digital loopback
  &T6 Start remote digital loopback
  &T7 Start digital loopback with self-test
  &T8 Start analog loopback with self-test
&Wn   Save current working RAM settings
&W0   Save RAM settings to NVRAM profile 0 (Y0)
&W1   Save RAM settings to NVRAM profile 1 (Y1)
&Xn   Synchronous timing source
  &X0 Use modem X-mit clock
  &X1 Use terminal X-mit clock
  &X2 Use modem receiver clock
&Yn   Break handling. Destructive breaks clear
the buffer, expedited breaks are sent immediately
to remote system.
  &Y0 Destructive, don't send break
  &Y1 Destructive expedited - Default
  &Y2 Non-destructive, expedited
  &Y3 Reserved
&Zn=L   Store last-dialed phone number in NVRAM at pos n
&Zn=s   Write phone number(s) to NVRAM at pos n (0-3),
36 characters maximum
&Zn?   Display phone number in NVRAM at pos. n (n=0-3)
%Rn   Remote access to Rack Controller Unit (RCU)
  %R0 Disabled
  %R1 Enabled
%T   Enable Touch Tone recognition

S-Register Settings - Functions

S-Register Value Modem Function/Option
S1   Count and stores numer of incoming rings
S2   Define escape code character - Default = + (43)
S3   Define ASCII (CR) carrige return (13)
S4   Define ASCII (LF) line feed (10)
S5   Define ASCII (BS) Backspace (8)
S6   Number of seconds wait before dial (2)
S7   Number of seconds wait for carrier (30)
S8   Duration (sec) for pause (,) option in Dial
command and pause between command re-executions
for Repeat (>) command.
S9   Duration (.1sec units) of remote carrier signal
before recognition. (6)
S10   Duration (.1sec units) modem waits after loss of
carrier signal before go on hook. (7)
S11   Duration and spacing (ms) of dialed Touch-Tones
(DTMD-tone) (70)
S12   Guard time (in .02 sec units) for escape code
sequence (+++) (50)
S13   Bit-mapped register (0)
  1 Reset when DTR drops
  2 Auto answer in originate mode
  4 Disable result code pause
  8 DS0 on DTR low-to-high
  16 DS0 on power up, ATZ
  32 Disable HST modulation
  64 Disable MNP level 3
  128 Watchdog hardware reset
S15   Bit-mapped register (0)
  1 Disable high-frequency equalization
  2 Disable on-line fallback
  4 Force 300-bps back channel
  8 Set non-ARQ x-mit buffer to 128 bytes
  16 Disable MNP level 4
  32 Set DEL as Backspace key
  64 Unusual MNP incompatibility
  128 Custom applications only
S16   Bit-mapped register (0)
  1 Analog loopback
  2 Dial test
  4 Test pattern
  8 Initiate remote digital loopback
  16 Reserved
  32 Reserved
  64 Reserved
  128 Reserved
S18   &Tn Test timer, disabled when set to 0 (0)
S19   Set inactivity timer in minutes (0)
S21   Length of Break, DCE to DTE, in 10ms units
S22   Define ASCII XON (17)
S23   Define ASCII XOFF (19)
S24   Duration (20ms units) of pulsed DSR when modem
is set to &S2 or &S3 (150)
S25   Delay to DTR in 10ms units (5)
S26   Duration (10ms units) of delay between RTS and
CTS, synchronous mode (1)
S27   Bit-mapped register (0)
  1 Enable V.21 modulation 300 bps
  2 Enable unencoded V.32 moulation
  4 Disable V.32 modulation
  8 Disable 2100 Hz answer tone
  16 Disable MNP handshake
  32 Disable V.42 Dtect phase
  64 Reserved
  128 Unusual software in compatibility
S28   Duration (.1sec units) of V.21/23 handshake delay
S32   Voice-Data switch options (1)
  0 Disabled
  1 Go off hook in originate mode
  2 Go off hook in answer mode
  3 Redial last dialed number
  4 Dial number stored at position 0
  5 Auto answer toggle On/Off
  6 Reset modem
  7 Initiate remote digital loopback
S34   Bit-mapped register (0)
  1 Disable V.32bis
  2 Disable enhanced V.32 mode
  4 Disable quick V.32 retrain
  8 Enable V.32 modulation
  16 Change MR LED to DSR
  32 Enable MI/MIC
  64 Reserved
  128 Reserved
S38   Duration(sec) before disconnect when DTR drops
during an ARQ call (0)

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