3Com U.S. Robotics 56K Voice User Manual page 66

&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.)
&N0 Connection speed is determined by the remote modem
&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
&N13 26,400 bps
&N14 28,800 bps
&N15 31,200 bps
&N16 33,600 bps
&N17 28,000 bps
&N18 29,333 bps
&N19 30,666 bps
&N20 32,000 bps
&N21 33,333 bps
&N22 34,666 bps
&N23 36,000 bps
&N24 37,333 bps
&N25 38,666 bps
&N26 40,000 bps
&N27 41,333 bps
&N28 42,666 bps
&N29 44,000 bps
60 56K Voice Faxmodem Internal - User's Guide
Technical Reference