I have Ericsson H5321gw WWAN modem (USB ID 0bdb:1926) on my Lenovo X230 laptop. I've got it working momentarily using NetworkManager GUI on Gnome3. Normally I can make it connect for a few minutes only to see the whole device being removed from NetworkManager later by itself. So technically it is working, but somehow the device keeps getting removed after a while (causing disconnection, of course). Initially I thought this might be an issue of USB Autosuspend power saving functionality but I have tried setting it off like so:
for i in /sys/bus/usb/devices/*/power/autosuspend; do echo -1 > $i; done
I have Debian Jessie with 3.10-3-amd64 kernel.
This is an example log from test where I got disconnected right away after connecting: http:// pastebin.com/ bGbTHGri (url pasting limit, sorry)
This is another test where I got disconnected after being connected for about 2 minutes: