This found in computers such as the Transmeta based A530 laptop and perhaps A531Laptops. DSE's transmeta laptop was based on the A531 model.
It seems the modem will work with the smartlink driver, slmodem.
There should be a driver for this in ubuntu already. You'll need to configure your sources.list to include 'multiverse', then you can install the sl-modem-daemon package.
Alternatively, look at 
http://ubuntuguide.org/#installsmartlinkdriver
References:
Part of CategoryPciDevice
No page links to 5457.
