0800 freephone numbers are free to call from a UK landline and are typically used to attract sales. OFCOM will change regulations shortly so calls to these numbers will also be free when calling from a UK mobile.
USA toll free numbers are free to call from anywhere in mainland USA. These numbers are normally used for sales, technical support and customer service lines.
International toll free numbers are free to call from a specified country. (Freephone numbers are available for over 80 countries around the world.)
Buy only one telephone number that is free to call from over 40 different countries.