Thanks for all the replies - great forum!

I had worked out that connecting the NIT to a USB modem stick would probably need a powered hub. The one I have says 5V DC and probably doesn't need a lot of juice so it might be feasible and portable. The main stumbler seems to be the software on the NIT. I saw elsewhere that Ubuntu can run on N800 and that may already have the right code...

My reluctance on doing it via a phone is the number of posts I see saying that "I bought xxxx phone but it didn't work or the provider blocks this type of use"

On the other hand I suppose I would have to buy the same USB modem in Italy or whatever which is probably more expensive than just getting a SIM card and putting it in a mobile.

Anyway I will report back how I get on... probably take me a while though!