CONNECTIONS
Purpose	Location	Purpose	Location
Line out	CN1	Line in	CN2

BASE I/O ADDRESS SELECTION
Port	SW1/A	SW1/B
COM1: (3F8h)	On	On
» COM2: (2F8h)	Off	On
COM3: (3E8h)	On	Off
COM4: (2E8h)	Off	Off

INTERRUPT SELECTION
IRQ	SW1/C	SW1/D	SW1/E	SW1/F
2	On	Off	Off	Off
» 3	Off	On	Off	Off
4	Off	Off	On	Off
5	Off	Off	Off	On

ACCEPT RELIABLE MODE
Type:	Immediate
Format:	AT [cmds] \Un
Example:	AT \U<CR>
Description:	Accepts remote modem’s request for reliable link.

AUTO-RETRAIN - FALLBACK/FALLFORWARD
Type:	Configuration
Format:	AT [cmds] %En [cmds]
Example:	AT %E1 <CR>
Description:	Controls auto-retrain mode and fallback/fall forward.
Command	Function
%E0	Auto-retrain disabled.
» %E1	Auto-retrain enabled.
%E2	Fallback/fall forward enabled.

BIT-MAPPED REGISTER S14
Format		AT [cmds] S14? [cmds]
Example:		ATS14?<CR>
Default:		Read only
Range:		0-255
Unit:		Bit-mapped.
Description:		Displays echo, result codes, result code display, dial mode, and answer/originate mode.
Bit	Value		Function
0	1		Not used.
1	0 » 1		Command echo disabled. Command echo enabled.
2	» 0 1		Result codes enabled. Result codes disabled.
3	0 » 1		Display result codes in numeric format. Display result codes in verbose format.
4	0		Not used.
5	» 0 1		Tone dial enabled. Pulse dial enabled.
6	0		Not used.
7	0 » 1		Answer mode enabled. Originate mode enabled.

BIT-MAPPED REGISTER S21
Format		AT [cmds] S21? [cmds]
Example:		ATS21?<CR>
Default:		Read only
Range:		0 - 255
Unit:		Bit-mapped
Description:		Displays low DTR action, DCD signal, DSR signal, and the Long Space Disconnect function.
Bit	Value		Function
2 - 0	010		Not used.
4, 3	00 01 » 10 11		DTR signal ignored. Modem goes to command mode on low DTR. Modem disconnects on low DTR. Auto-Answer is disabled. Modem is initialized on low DTR.
5	0 » 1		DCD forced high. DCD normal.
6	» 0 1		DSR forced high. DSR normal.
7	» 0 1		Long Space Disconnect function disabled. Long Space Disconnect function enabled.

BIT-MAPPED REGISTER S22
Format		AT [cmds] S22? [cmds]
Example:		AT S22?<CR>
Default:		Read only
Range:		0 - 255
Unit:		Bit-mapped.
Description:		Displays volume and speaker settings, result codes, and make/break pulse ratio.
Bit	Value		Function
1, 0	00 01 » 10 11		Lowest volume setting. Low volume setting. Medium volume setting Highest volume setting.
3, 2	00 » 01 10 11		Speaker disabled. Speaker enabled until carrier signal detected Speaker enabled. Speaker enabled following dialing, then disabled after carrier signal detected.
6, 5 ,4	000 100 101 110 » 111		Busy and dialtone detection disabled, result codes 0-4 enabled. Busy and dialtone detection disabled, result codes 0-5, 10 enabled. Busy tone detection disabled, dialtone detection enabled, result codes 0-6, 10 enabled. Busy tone detection enabled, dialtone detection disabled, result codes 0-5, 7, 10 enabled. Busy and dialtone detection enabled, result codes 0-7, 10 enabled.
7	» 0 1		39/61ms at 10pps (North America) 33/67ms at 10pps (Europe)

BIT-MAPPED REGISTER S23
Format		AT [cmds] S23? [cmds]
Example:		ATS23?<CR>
Default:		Read only
Range:		0-255
Unit:		Bit-mapped
Description:		Displays DTE rate and parity.
Bit	Value		Function
0	1		Not used.
3, 2, 1	000 001 010 011 100 101 110 111		Sets serial port speed to 0-300bps. Sets serial port speed to 600bps. Sets serial port speed to 1200bps. Sets serial port speed to 2400bps. Sets serial port speed to 4800bps. Sets serial port speed to 9600bps. Sets serial port speed to 19200bps. Sets serial port speed to 38400bps.
5,4	» 00 10		Parity even. Parity odd.
7, 6	0		Not used.

BIT-MAPPED REGISTER S27
Format		AT [cmds] S27? [cmds]
Example:		ATS27?<CR>
Default:		Read only
Range:		0 - 255
Unit:		Bit-mapped
Description:		Displays protocol type.
Bit	Value		Function
1 - 0	0		Not used.
5 - 3	0		Not used.
6	0 » 1		Select CCITT protocols. Select Bell protocols.
7, 2	0		Not used.

BREAK SEND
Type:	Configuration
Format:	AT [cmds] \Bn [cmds]
Example:	AT \B3 &W<CR>
Default:	3
Range:	1-9
Unit:	.1 second
Description:	Sends break to modem.

BREAK TYPE
Type:	Configuration
Format:	AT [cmds] \Kn [cmds]
Example:	AT \K1 <CR>
Description:	Configures action of break signal.
Command		Break from DTE	Break from remote modem	Modem receives \B
\K0		Enter command mode, do not send break to remote modem.	Buffers cleared and break sent to DTE.	Send break to remote modem immediately, then enter command mode.
\K1		Buffers cleared and break sent to remote modem.	Buffers cleared and break sent to DTE.	Send break to remote modem immediately.
\K2		Enter command mode, do not send break to remote modem.	Send break to DTE immediately.	Send break to remote modem immediately, then enter command mode.
\K3		Send break to remote modem immediately.	Send break to DTE immediately.	Send break to remote modem immediately.
\K4		Enter command mode, do not send break to remote modem.	Break sent with received data to the DTE.	Send break to remote modem immediately, then enter command mode.
» \K5		Send break with transmitted data.	Break sent with received data to the DTE.	Send break to remote modem immediately.

COMPRESSION
Type:	Configuration
Format:	AT %Cn
Example:	AT *EC0 %C1 *AP0<CR>
Description:	Selects data compression.
Command	Function
%C0	Data compression disabled.
» %C1	Data compression enabled.

CONNECT MODE
Type:	Configuration
Format:	AT [cmds] \Nn [cmds]
Example:	AT \N1 DT555-1212<CR>
Description:	Sets connect mode.
Command	Function
\N0	Normal mode enabled.
\N1	Diagnostic mode, select this before selecting &T commands.
\N2	Reliable mode enabled.
» \N3	Auto-reliable mode enabled.
\N4	LAPM mode enabled.

CONVERT TO RELIABLE MODE
Type:	Immediate
Format:	AT [cmds] \Y [cmds]
Example:	AT \Y<CR>
Description:	Initiates reliable mode link.

EXTENDED RESULT CODES
Type:	Configuration
Format:	AT [cmds] \Vn [cmds]
Example:	AT \V1 %C1<CR>
Description:	Selects extended result codes.
Command	Function
\V0	Extended result codes disabled.
\V1	Reliable result codes enabled.
» \V2	Error correction and compression result codes enabled.
\V3	DTE speed result codes enabled.

FLOW CONTROL TYPE
Type:	Configuration
Format:	AT [cmds] \Qn [cmds]
Example:	AT \Q3 A <CR>
Description:	Sets type of flow control used by modem.
Command	Function
\Q0	Flow control disabled.
\Q1	XON/XOFF flow control enabled.
» \Q3	RTS/CTS flow control enabled.

INACTIVITY TIMER
Type:	Configuration
Format:	AT [cmds] \Tn [cmds]
Example:	AT\T5<CR>
Default:	0
Range:	0-42
Unit:	1 minute
Description:	Sets the length of time that the modem does not receive information before it disconnects.

MAXIMUM BLOCK SIZE FOR TRANSMISSION
Type:	Configuration
Format:	AT [cmds] \An [cmds]
Example:	AT \A3 &MB28800<CR>
Description:	Sets the maximum transmittable block size.
Command	Function
\A0	Maximum MNP block size is 64 characters.
\A1	Maximum MNP block size is 128 characters.
» \A2	Maximum MNP block size is 192 characters.
\A3	Maximum MNP block size is 256 characters.

ON-LINE IN RELIABLE MODE
Type:	Immediate
Format:	AT [cmds] \O
Example:	AT \O <CR>
Description:	Returns to on-line and requests reliable mode connection.

PROTOCOL/SPEED
Type:	Register
Format:	AT [cmds] S31=n [cmds]
Example:	AT S31=0 <CR>
Description:	Selects the maximum DCE speed.
Command	Function
» S31=0	Select last speed at AT command.
S31=3	Select 300bps speed.
S31=5	Select 1200bps speed.
S31=6	Select 2400bps speed.
S31=7	Select 4800bps speed.
S31=8	Select 7200bps speed.
S31=9	Select 9600bps speed.
S31=10	Select 12Kbps speed.
S31=11	Select 14.4Kbps speed.

RETURN TO RELIABLE MODE
Type:	Immediate
Format:	AT [cmds] \Z [cmds]
Example:	AT \Z <CR>
Description:	Ends reliable mode link, initiate return to normal mode.

TEST MODES
Format		AT [cmds] S16=n [cmds]
Example:		ATS16=40<CR>
Default:		0
Range:		0-125
Unit:		Bit-mapped
Description:		Controls loopback tests, analog, digital, remote digital, and self tests.
Bit	Value		Function
0	» 0 1		Local analog loopback not in progress. Local analog loopback in progress.
1	» 0		Not used.
5 - 1	0		Not used.
6	» 0 1		Local analog loopback w/ self-test not in progress. Local analog loopback w/ self-test in progress.

V.42bis COMPRESSION CONTROL
Type:	Configuration
Format:	AT [cmds] "Hn [cmds]
Example:	AT "H3 &W<CR>
Description:	Controls V.42bis data compression
Command	Function
"H0	V.42bis disabled.
"H1	V.42bis when transmitting enabled.
"H2	V.42bis when receiving enabled.
» "H3	V.42bis when transmitting/receiving enabled.

XON/XOFF PASS-THROUGH
Type:	Configuration
Format:	AT [cmds] \Xn [cmds]
Example:	AT \X1 O<CR>
Description:	Selects whether XON/XOFF signals are sent to remote modem.
Command	Function
» \X0	XON/XOFF signals trapped by local modem.
\X1	XON/XOFF passed through local modem.