Sierra's website says this device is compatible with Linux.

I did an install of Ubuntu 10.04 recently, and initially the Sierra USB thingy was working fine, but then it stopped. Fiddled around a little and I eventually got it to work again (I'm not sure that anything I did was actually responsible for this) but apparently it stopped working again shortly after I left.

A few weeks later I upgraded all the packages, something I hadn't done during the install, and the device started working again. I rebooted the machine several times and each time the connection came up reliably soon after I connected the device.

Now it's not working again. It's not working on my Debian machine either. But it works perfectly in any windows machine every single time, and I've carefully checked the APN, authentication and compression settings and made them the same under Linux (PAP only, no compression anywhere) but still no worky.

Any suggestions?