The Option N.V. modems appear at first as a
umass(4) device containing the Windows and MacOS drivers and, upon receipt of a SCSI “REZERO UNIT” command, will detach from the USB bus and reattach as a Wireless WAN modem. Unless disabled by clearing the
sysctl(8) variable
hw.uhso.autoswitch, the driver will handle that automatically.
The modems provide a number of IO channels spread over several USB interfaces which are mapped by function to a standard port number in each driver instance. The defined channels are:
Apart from the Network port, which is attached as a network interface, the ports are attached as
tty(4) devices using the port number as the minor device number.
Before the Network port can be used, the modem needs to be placed in connected mode and network settings subsequently retrieved using the proprietary “_OWANCALL” and “_OWANDATA” AT commands on the Control port.
Note that the Modem and Network ports should not be enabled at the same time for USB performance reasons.