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)