Quoted from the Skype (not 3) website:

3 Skypephone Terms
Available from 3 to new approved customers who purchase a 3 Skypephone and
register on selected 3 monthly or pre-paid price plans, subject to minimum
contract and regular top-up. Free calls are Skype-to-Skype calls and Skype
instant chat messages only from the 3 network or while roaming on a 3 sister
network. Fair use policy and terms apply. Visit the 3 website in your
country for details.

This would suggest free Skype calls on 3 networks abroad. I did not find
anything on 3 UK website to confirm this. Sounds too good to be true.

divoch