Toll free numbers are assigned to the country they originate and are not accessible internationally. There are some general exceptions to this rule. Canadian toll free numbers, for instance, are accessible from the US and vise versa.
There are other exceptions where toll free numbers in the US can be reached by some telecommunication providers in the United Kingdom and other countries. However, this usually is not the case, and it’s generally not free. This means the caller is charged for a regular US call even if they actually do reach a toll free number within a different country. It is best to assume, under most circumstances, that toll free numbers aren’t accessible from outside the country in which they are based.