3Com 56K CD when it disconnects, Mode during a call by dropping DTR, With the Hn command, Canada

B-6APPENDIX B: ALPHABETIC COMMAND SUMMARY

Command	Function
	&C1	Normal operations. The modem sends a CD signal
		when it connects with another modem and drops
		the CD when it disconnects.
&Dn	Control how the modem responds to Data Terminal Ready (DTR)
	signals.
	&D0	DTR is always ON (ignored).
	&D1	If issued before connecting with another device,
		the Business Modem can enter online Command
		mode during a call by dropping DTR.
		&D1 functions similarly to the escape code (+++).
		Return online with the On command, or hang up
		with the Hn command.
	&D2	Normal DTR operations. The modem will not
		accept commands unless your computer sends a
		DTR signal. Dropping DTR ends a call.
	&D2S13=1	Modem resets with DTR toggle
&Fn	Load one of the three configuration templates that are stored
	permanently in read-only memory. Appendix C, Flow Control
	Templates, lists the settings for each template.
	To load a template into current memory, enter AT&Fn. To write
	a template to NVRAM, enter AT&Fn&W.
	&F0 is always loaded into memory at power-on or when the
	RESET button is pressed.
	&F0	Load No Flow Control template settings.
	&F1	Load Hardware Flow Control template settings.
	&F2	Load Software Flow Control template settings.
&Gn	Set guard tones for international calls.
	&G0	No guard tone. Use this in the United States and
		Canada.
	&G1	This sets a 550 Hz guard tone, and is used in some
		European countries.
	&G2	This sets an 1800 Hz guard tone, and is used in
		the U.K. and some Commonwealth countries.
		&G2 requires the B0 setting.
&Hn	Transmit data flow control. Prevents the modem’s buffer for
	data transmitted to the modem by its attached computer from
	overflowing.
	&H0	Disable transmit data flow control.