IBM 8088 Low speaker volume, Internal speaker on until carrier detected, Sr?, Sr=n, Detection

Command		Function
	H1	Force modem off-hook (make busy)
		Note: H1 command is not supported for Italy
I_	I0	Display product-identification code
	I1	Factory ROM checksum test
	I2	Internal memory test
	I3	Firmware ID
	I4	Reserved ID
L_	L0	Low speaker volume
	L1	Low speaker volume
	L2	Medium speaker volume
	L3	High speaker volume
M_	M0	Internal speaker off
	M1	Internal speaker on until carrier detected
	M2	Internal speaker always on
	M3	Internal speaker on until carrier detected and
		off while dialing
N_		Included for compatibility only, provides no
		effect
O_	O0	Return to Data Mode
	O1	Return to Data Mode and initiate an equalizer
		retrain
P		Set Pulse dial as default
Q_	Q0	Modem sends responses
Sr?		Read and display value in register r.
Sr=n		Set register r to value n (n = 0-255).
T		Set Tone Dial as default
V_	V0	Numeric responses
	V1	Word responses
W_	W0	Report DTE speed only
	W1	Report line speed, error correction protocol,
		and DTE speed.
	W2	Report DCE speed only
X_	X0	Hayes Smartmodem 300 compatible
		responses/blind dialing.
	X1	Same as X0 plus all CONNECT
		responses/blind dialing
	X2	Same as X1 plus dial tone detection
	X3	Same as X1 plus busy detection/blind dialing
	X4	All responses and dial tone and busy signal
		detection
Z_	Z0	Reset and retrieve active profile 0
	Z1	Reset and retrieve active profile 1

36User Guide