It's nice to have a 3G/GPS/HSPA+ card in your laptop for a working data connection on the go (without WiFi). For the ex-IBM/now Lenovo ThinkPad X1 Carbon, this is the Ericsson H5321gw. Here is how to get it working with Linux (here Ubuntu 14.04.2, others likely similar):
$ lsusb | grep Ericsson
Bus 002 Device 002: ID 0bdb:193e Ericsson Business Mobile Networks BV
options cdc_ncm prefer_mbim=N
$ sudo cp /lib/udev/rules.d/77-mm-ericsson-mbm.rules /etc/udev/rules.d/ $ sudo nano /etc/udev/rules.d/77-mm-ericsson-mbm.rules
Now find a line with the comment "H5321gw", and copy one of the (two, in my case) existing rules and replace idVendor with 0bdb and idProduct with 193e, as per lsusb’s output above; so it will be:
ATTRS{idVendor}=="0bdb", ATTRS{idProduct}=="193e", ENV{ID_MM_ERICSSON_MBM}="1
The latter is very important as it avoids USB disconnects (Google, index this!) - curiously, it does work without this - for about 10s or so. So the USB device is found and then something disconnects it. If someone reading this can enlighten me more about the inner workings of USB / udev on Linux and can can explain this, I'd love to learn.
Reboot (for the modprobe.d thing; the udev is hot reloaded). Now use Modem Manager (tray icon), which shows “Mobile Broadband” (new), with the name of your provider greyed out. You create a New Connection, choose country Switzerland, provider... I had to change to APN, e.g. for Orange in Switzerland its "internet" - you can find this e.g. on your Android settings for your phone's SIM card.
I've opened this LP bug so that perhaps this can be set by default so that it works out of the box.
BTW: modem-manager-gui is a neat companion to standard Network Manager in this context.
PS: ACK tx to this post (hard to find, thus replicated here) and this site, and you're welcome there.
PPS: Yeah, I do know you also can tether the phone via cable (cumbersome every morning in transit..), or via Bluetooth (can't get that to work on Linux :), or via WiFi Hotspot sharing (sucks battery, hate having to fumble out the phone and open Settings etc. 'just' to get online - its one click with this solution).