Introduction to Data Communication for Linux Users
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AT Command Set (Partial listing)

Command		Function
A		Answer incoming call
B0		Use V.22 1200 baud connection
B1		Use Bell 212A 1200 baud connection
Dxxx-xxxx		Dials a phone number xxx-xxxx
		D can be followed by:
		! Goes on hook for time given in S29
		, Pauses during dial (pause time is in S8)
		S=#{#=0-3} Dials number stored in &Z#
		; (comes after dial string) Return to
		command mode after dialing
		@ Waits for 5 sec of silence before dialing
L		Redials last number dialed
P		Pulse dial
R		Accept command, but don't act on it [...]
W		Wait for dial tone
^		Turn on call tone
E0		Echo off - no command characters
E1		Echo command characters
H0		Hang up
H1		Off hook (same as hang up)
I0		Info - returns product code
I1		Info - Returns ROM checksum
I2		Info - Checks ROM checksum and returns OK or ERROR
I3		Info - Returns firmware revision code
I4		Info - Returns modem ID string
I5		Info - Returns country code
I6		Info - Returns data pump info
L0		Sets speaker volume to lowest
L1		Sets speaker volume to low
L2		Sets speaker volume to medium
L3		Sets speaker volume to highest
M0		Speaker off
M1		Speaker is on until a carrier detect
M2		Speaker is always on
M3		Speaker is on during answering only
N0		Disables automatic modulation negotation
O0		Puts modem in data mode
O1		Takes modem out of data mode
P		Pulse dialing
Q0		Sets DTR line
Q1		Clears DTR line
S#		Make S-register # default register
S#=x		Set S-register # to x
S#?		Returns value of register #
T		Tone dialing
V0		Numeric responses
V1		Verbose responses
W0		Returns computer-modem speed
W1		Returns tranfer rate and error correction protocol
W2		Returns modem-modem speed
X0		Verbose error codes
X1		X0 responses and connect speed
X2		X1 responses and NO DIALTONE
X3		X1 responses and BUSY
X4		All responses
Y0		Disable disconnection on pause
Y1		Enable disconnection on pause
Z0		Sets modem to profile 0 (set in &W0)
Z1		Sets modem to profile 1 (set in &W1)

The following AT commands are not part of the original specification and are called the Extended AT command set. Each command is preceded by a "&" symbol.

&C0		Sets DCD on
&C1		Sets DCD to follow the actual carrier
&D0		DTR active
&D1		DTR drop as an escape sequence
&D2		DTR drop as a hang up command
&D3		DTR drop as a reset; loads profile from &Y
&F		Loads the factory profile (may be many)
&G0		Disables gaurd tone
&G1		Disables gaurd tone
&G2		Enables 1800 Hz guard tone
&K0		No flow control
&K3		Hardware flow control
&K4		Software (XON/XOFF) flow control
&M0		No error correction, no speed control
&Q0		Does same thing as &M0
&Q5		Modem negotiates error correction
&Q6		&M0 with speed buffering
&S0		Data Set Ready active
&S1		DSR active after answer detected until carrier is lost
&T0-8		{Engineering tests}
&V		Returns profiles [&Y] and stored numbers [&Z]
&W0		Save current config as profile 0
&W1		Save current config as profile 1
&Y0		Modem uses profile 0 on startup
&Y1		Modem uses profile 1 on startup
&Z#=x		Set stored number (0-3) to #

Introduction to Data Communication for Linux Users
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