Connect modem to host OS.Open VirtualBox, go to the setting of your virtual machine.
Go to Serial Ports and set the setting as below:
Enable Serial Port.
Set Port Number: “port number inside the guest OS”
Port Mode: Host Device
Path/Address: “port number of modem that is connected to host OS”. Click OK
note: if this step is skipped, hyper terminal will have no response if connected to the “Sierra Wireless AT Command Port”
Run the virtual machine.
Go to device manager in VirtualBox to check the COM Port. In this example, the MOBITEK S80 Modem that is connected to the USB port (COM6) of host machine, the USB port is then mapped serial port (COM1) of VirtualBox.
In VirtualBox, the modem is connected to COM1 which is the serial port .
In the host machine, the same modem is connected to COM6 which is the USB port.