What does the WWAN Modem device do?



According to the mangOH Green User Guide, the Device Manager of my Windows computer displays a list of Sierra Wireless devices when I connect the board via USB: WWAN Modem, DM Port, NMEA Port, Mobile Broadband Network Adapter, …
I’m able to setup a mobile connection on my computer and use the SIM of the mangOH to go on the internet.

Even if I disable the Sierra Wireless WWAN modem in the Device Manager, my mobile connection stays available.
How is this possible?
If the WWAN device is not needed for the mobile connection, what is used for then?