US Robotics Sportster Operating Instructions Manual page 149

ON Disables auto answer
Factory
Switch Setting Function
6 OFF Carrier Detect (CD) Override
OFF Modem sends CD signal when it connects with another modem, drops
ON CD always ON (Override)
7 OFF Power-on and ATZ Reset Software Defaults
OFF Loads Y or Y1 configuration from user-defined nonvolatile memory
ON Loads &F0 Generic template from read only memory (ROM)
8 ON AT Command Set Recognition
OFF Disables command recognition (Dumb Mode)
ON Enables recognition (Smart mode)
T Q
ECHNICAL UICK
CD on disconnect
(NVRAM)
R
EFERENCE
145