Toshiba Portege 3500 User Manual page 200

AT Commands
H-10
Disabled: The modem ignores any busy tones it receives.
Enabled: The modem monitors for busy tones.
Result Codes:
n = 0, 1, 2, 3, 4, 5
OK
Otherwise
ERROR
The modem performs a soft reset and restores (recalls) the
configuration profile according to the parameter supplied. If no
parameter is specified, zero is assumed. Either Z0 or Z1 restores
the profile.
Result Codes:
n = 0, 1
OK
Otherwise
ERROR
Data Carrier Detect is a signal from the modem to the computer
indicating that a carrier signal is being received from a remote
modem. DCD normally turns off when the modem no longer
detects the carrier signal.
&C0
The state of the carrier from the remote modem is
ignored. DCD circuit is always on.
&C1
DCD turns on when the remote modem's carrier
signal is detected, and off when the carrier signal is
not detected (default).
Result Codes:
n = 0, 1
OK
Otherwise
ERROR
Portégé 3500