OpenHandset and CloseHandset

OpenHandset puts the modem into a mode that will allow playing audio (wave files) to the handset.

CloseHandset resets the modem to class 0.

One or more command strings can be used.

HKR, OpenHandset,    1,, "at#cls=8"
HKR, OpenHandset,        2,, "at#vls=1"
HKR, CloseHandset,    1,, "at#cls=0"

These commands are used to play audio through the handset while there is no active call.