A Canadian or US Toll Free number may be reachable by anyone in North America unless the owner of the Toll Free number has defined a geographical limitation. As an example, a company in Toronto who may also have a local Toronto number, may make their Toll Free number inaccessible from Toronto in order to get callers to call them on their local number.
In addition, Canadian & US Toll Free numbers can also be reached from Public Telephones without payment. However this feature may also be limited by the owner of the Toll Free number.
Callers from outside of Canada or the US may be able to call you on your Toll Free number, depending on the country and carrier they are calling from. However by no means does this mean that they will not be charged for the call. Some carriers in some countries will route the call to you, but may still charge standard international rates to the caller. There is most certainly no guarantee that your Toll Free number will be accessible from other countries.