Is a 1-866 number toll-free from Mexico?

1-866 is a toll-free prefix in the United States. You may be able to dial it from Mexico by dialing it as if it were an ordinary geographic number in the US. Although a few US toll-free numbers have special arrangements to make the numbers toll-free also from Mexico (dialing 00 1 8xx etc.), most do not. If the call does go through, you will most likely pay the international call charges for a call to the U.S.