Fedora Networking :: Using NMCLI To Bring Up Mobile Internet Connection

I can use nmcli to bring down and back up again my wireless connections but it doesn't seem to work with my "Mobile Broadband" connections. It works to bring down my mobile internet with :

Code:
nmcli con down id OptusInet
But when I try to bring it up again with :
Code:
nmcli con down id OptusInet
It says :

Code:
Error: No suitable device found: no device found for connection 'OptusInet'.
Even when I add the device with :

Code:
nmcli con up id "OptusInet" iface ttyUSB0
It says :

Code:
Error: No suitable device found: device 'ttyUSB0' not compatible with connection 'OptusInet'.
Am I doing something wrong?? Any ideas anyone??

Device info for my mobile device :
Code:
[my_prompt]$ nmcli -p dev list .....