USRobotics V.34 - Manual (Page 179)

COURIER HIGH SPEED MODEMS
F-14 Synchronous Operations
Hanging Up
The modem remains online until the remote modem disconnects
or your software causes the DTE to drop the Data Terminal
Ready signal (DTR). The Courier sends the NO CARRIER
result code if result codes are enabled, and returns to
asynchronous Command mode.
Testing and Inquiry Commands
The modem testing commands (&T n) and inquiry commands
(I n) cannot be used when the modem is operating in
synchronous mode.
ENABLING REMOTE ACCESS
Because synchronous equipment cannot use AT commands to
configure modems, a special function was designed so the
modem can receive AT commands remotely. To do this, the
modem must be placed in remote access mode with the
voice/data switch.
Press and hold down the voice/data switch while powering on
the modem. Pressing the switch during power-on causes the
modem to perform its normal self-test, enable Auto Answer,
enable Remote Access (by changing the S41 setting to 1), and
disable password security.
WARNING: If you enable remote access by pressing the
voice/data switch while powering on the modem, previously
set passwords will be erased.