I've just bought a Tesco Internet Phone Adapter IPA-1000 (it was on sale, and I had some Tesco Clubcard Vouchers to use up). Some notes:
When it's first plugged in, it stays flashing red for awhile, this is it downloading firmware.
It appears to really be a Virbiage 3010. Freshtel have the manual - which importantly includes the username and password for the web interface to the device (something distinctly lacking in the Tesco manual).
I've got it running with asterisk - fairly simple with the web interface. Just go to the provider tab, enter the server name/ip address, username and password and it connects.