User`s manual

Ln
Control Speaker Volume
L0
Low volume.
L1 Low volume.
L2 Medium volume. (default)
L3 High speaker volume.
Mn
Monitor Speaker On/Off
M0 Speaker is always off.
M1 Speaker is off while receiving carrier. (default)
M2 Speaker is always on.
M3
Speaker disabled while dialing or receiving carrier
Nn Select Data Rate Handshake
This command specifies whether the resulting modem-to-modem data rate can be
different than the local DTE-to-modem data rate.
N0 When originating or answering, handshake only at
the DTE-to-modem data rate.
N1 When originating or answering, begin handshaking
at the DTE-to-modem data rate. If the remote modem
does not support the local DTE-to-modem data rate.
fall down to the highest compatible data rate. (default)
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COMMAND REFERENCE - 2