I used 886 in place of 833 last night and it worked fine. From a Mexican LL with prefix 376. Had a long and enjoyable phone call.
Have used others according to the list above and other such lists, and every one has worked out fine. These lists can easily be Googled at any time, from any online connection.
Before I learned of these substitute toll free prefixes for outgoing Mexican LL calls to toll free numbers, it was a mess! But these lists will get you through it.