I was told that I could call toll free directory assistance in the US from México. I tried it and it worked. They have English operators and they gave me a number to a bank that I couldn't get before. It works just like the US except that you dial 01-800-555-1212. They referred me to dial 001-877-208-7697 to make free calls to banks and government agencies in the USA and Canada. And I have used 001-888-222-1516 to make personal collect, credit card or third party calls at a rate a lot less than any other phone company. If calling from the USA/Canada, simply drop the double "00" and dial normally as you would a toll free number from the states. They also have a website at:
www.Visa.Assets.Com with a bunch of other information for tourists and Americans/Canadians traveling/living in Mexico, or the USA/Canada. I though it would be helpful.