there are some capes available that provide support for mobile communication via GSM/GPRS/LTE.
As the software support may be the bottleneck, my question: is any of these capes supported by Ubuntu for the BB? If yes, which of them can be used for mobile communication?
I doubt you will find any.
What we use is a failover switch with a sim card, just connect it to your ethernet port. Best part about this, it is a NO BS solution, it works with out all the headaches.
In theory yes it should work. I don’t use a Desktop on any BB, however if that is what you want, look at ModemManger & NetworkManager. I seem to recall using a USB 3G modem on Linux a few years ago and it pretty much just worked. I think I used ModemManager then.
ModemManager can also be used from the command line so should be scriptable.
In the past I have used the qmi stuff for Qualcomm based modems. This was on a very minimal OS without DBUS so couldn’t use ModemManager. It was very easy to get up and running. How to set up a simple data connection over Qualcomm QMI interface using libqmi and driver qmi_wwan in Linux
Failing that you can do it yourself with PPP and CHAP. You will probably be able to Google up some examples.