Toshiba V.90 - Manual (Page 45)

AT Commands
AT command formats
26
&Dn Data Terminal Ready (DTR) control
This command interprets how the modem responds to the state of
the DTR signal and changes to the DTR signal.
Result Codes:
&F Load factory settings
This command loads the configuration stored and programmed at
the factory. This operation replaces all of the command options
and the S-Register settings in the active configuration with factory
values.
&Gn V.22bis guard tone control
This command determines which guard tone, if any, to transmit
while transmitting in the high band (answer mode). This
&D0 Ignore. The modem ignores the true status of DTR
and treats it as always on. This should only be used if
your communication software does not provide DTR
to the modem.
&D1 If the DTR signal is not detected while in online data
mode, the modem enters command mode, issues an
OK result code, and remains connected.
&D2 If the DTR signal is not detected while in online data
mode, the modem disconnects (default).
&D3 Reset the modem on the on-to-off DTR transition.
OK n=0,1,2,3
ERROR Otherwise
&F Recall factory setting as active configuration.