Hi David,
Try Pipex dial:-
www.dial.pipex.com
They have a global roaming service with local Points of Presence in most places. I use them for work, and haven't found anywhere yet where you can't find a number (usually local).
You might want to post this in Computers / Internet as there are many PPRune computer gurus that frequent that forum who will probably be able to give better advice.
Good Luck,
F - Wyg