3Com 56k User's Manual And Reference page 60

&Mn Sets Error Control (ARQ) for
connections at 1200 bps and higher
&M0 Normal mode, error control
disabled
&M1 Reserved
&M2 Reserved
&M3 Reserved
&M4 Normal/ARQ
&M5 ARQ mode
&Nn Sets connect speed, if connection
cannot be made at this speed, the
modem will hang up. When used in
conjunction with &Un and &Un is
greater than 0, &Nn sets the ceiling
connect speed. &Un sets the floor
connect speed. (See also the table in
the &Un section.)
Note: &N17 through &N39 apply only to
V.90 products.
&N0 Connection speed is determined
by the remote modem
56
Technical Reference
&N1 300 bps
&N2 1200 bps
&N3 2400 bps
&N4 4800 bps
&N5 7200 bps
&N6 9600 bps
&N7 12,000 bps
&N8 14,400 bps
&N9 16,800 bps
&N10 19,200 bps
&N11 21,600 bps
&N12 24,000 bps