My Android device shows up with a relatively usual device name, enp0s19f2u3. Enp devices are picked up by the webconfig. If it shos up as a usbX type of device it will not show unless you do a one line hack to the is_configurable() function in /usr/clearos/apps/network/libraries/Iface.php. I'd be curious to know what the iPhone shows up as.

I guess you'll need to connect your phone to the server and have a look at "dmesg" to see what shows up when internet sharinig by USB is enabled. Then it is a question of seeing if any drivers load or try rebooting and see if any drivers load and show up in the webconfig as network interfaces. It would be a NAT'd connection so only any good for outbound services. I may try with an Android device sometime - I don't have am iPhone.