I have just installed Ubuntu 13.04 Raring. Now I'm facing a problem with my Huawei EC156 modem.
At first it will work properly but it will disapear from network-manager if the modem is disconnected after online or removed from the USB slot. The 'Enable Mobile Broadband' would also disappear from Network Manager. The modem will appear again if I use it from Windows and then run it again on Ubuntu.
If the modem is detected correctly, dmesg would show something like this:
New USB device found, idVendor=12d1, idProduct=140c
but if it is not detected, dmesg would show this result:
New USB device found, idVendor=12d1, idProduct=1505
I have never seen this problem before in previous versions of Ubuntu. How can I fix it?