USRobotics V.34 user manual Options are as follows

COURIER HIGH SPEED MODEMS

The options are as follows.

&N1	300 bps	&N9	16.8K bps (HST, terbo,
&N2	1200 bps		V.FC, and V.34 only)
&N3	2400 bps	&N10	19.2K bps (terbo, V.FC,
&N4	4800 bps		and V.34 only)
&N5	7200 bps	&N11	21.6K bps (terbo, V.FC,
&N6	9600 bps		and V.34 only)
&N7	12K bps	&N12	24K bps (V.FC and V.34 only)
&N8	14.4K bps	&N13	26.4K bps (V.FC and V.34 only)
		&N14	28.8K bps (V.FC and V.34 only)

&Pn This command sets the ratio of the off-hook/on-hook (make/ break) interval for pulse dialing. The default sets the modem for use in North America. The ratio must be changed if the modem is used in the United Kingdom and some Common- wealth countries.

&P0	Make/break ratio, U.S./Canada: 39%/61%. Default.
&P1	Make/break ratio, United Kingdom, some
	Commonwealth countries: 33%/67%.

&Rn Received data hardware (RTS) flow control

&R0	Delay Clear to Send Response after Request to Send
	signal (RTS/CTS delay).
&R1	The modem ignores RTS. This setting is required if your
	computer or terminal or software does not support RTS.
&R2	Hardware flow control of received data enabled.
	Default. The modem sends data to the computer or
	terminal only on receipt of the RTS signal.

&Sn The modem sends the computer or terminal a Data Set Ready (DSR) signal via the RS-232 interface. (Data Set is industry jargon for modem.)

&S0	DSR is always ON (override). Default.
&S1	In Originate mode, the modem sends the DSR after it
	dials, when it detects the remote modem's answer tone.
	In Answer mode, the modem sends the DSR after it
	sends an answer tone.

C-14 Alphabetical Command Summary