Hello gvendur,
To Activate your copy of Vista, you will need to use the Activate by Phone method. But if the phone number for the Iceland Activation call center isn't working, my suggestions would be to either
a) Use the phone number for the next nearest location.
or
b) Contact the Microsoft home office in Iceland (http://www.microsoft.com/iceland/) and get the updated number for the Activation call center.
Thank you,
Darin Smith
WGA Forum Manager