Some time ago I wrote about using mobile broadband with Ubuntu, and I was very hopeful at that time that it would soon be "plug in and click to connect". Unfortunately it hasn't turned out that way, at least yet. Considered in the light of my original goal, which was simply to get my Sierra Wireless Air Card 880 working with Ubuntu, it is still a major win, because I can do that - and I do so, pretty much every day. But at least for the Swisscom version of this card, and I strongly suspect for most versions other than the AT&T "branded" card, it still takes a lot more fiddling than it should.
The problem is with the APN setup in the connection procedure. The Network Manager seems to be using an incorrect command, or an incorrectly formatted command, and the APN setup fails. If I use the wvdial utility, with the correct /etc/wvdial.conf configuration, it connects with no problem. Furthermore, once I have connected using wvdial (and disconnected again, of course), if I remove the APN specification from the Network Manager configuration of the Mobile Broadband device, I can then connect using Network Manager.
It would be nice if this were eventually corrected, but I doubt if that is going to happen anytime soon. So I will include the wvdial.conf file that works for me here, and some brief instructions to accompany it. For carriers other than Swisscom, you would have to contact your service provider to get the correct APN value to replace "gprs.swisscom.ch".
Content of /etc/wvdial.conf:
Phone = *99***1#
Username = gprs
Password = gprs
Dial Command = ATDT
Modem = /dev/ttyUSB0
Baud = 460800
Init1 = ATZ
Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
ISDN = 0
Modem Type = Analog Modem
New PPPD = yes
In addition to entering this configuration file, it is necessary to remove any PIN code on the Air Card. Once that is done, the connection can be established with the command "sudo wvdial". However, because the Network Manager isn't aware of connections set up this way, applications such as Firefox will not be aware of the connection, and thus will start in "offline" mode. You can generally get around that by going to the "File" menu and un-checking "work offline".
Once the card has been properly configured and connected using wvdial, it should then be possible to connect using Network Manager. First, right-click on the Network Manager icon in the Gnome panel, and choose "Edit Connections". Then select "Mobile Broadband", click the profile for your card (there should only be one), choose "Edit", and then remove any value in the "Advanced/APN" field. Save and exit. Then you should be able to connect by simply clicking on the Network Manager icon, and selecting the Mobile Broadband interface. The advantage of doing this is that other programs will see that the network connection exists, and thus will start up in online mode.