Toll free numbers absolutely do work at Public Mobile with provincial calling plans. As for other carriers, they ALL allow calling (at the same prices as local calls) to toll free numbers. Public Mobile is no different I can confirm that 1-800 numbers are included on province-wide plans.
In fact, 1-800, 1-888, 1-877, etc numbers are even included on all the Canadian carriers even on local calling plans. We have to remember that "toll free" does not mean that a call is "free". It just means that there are no long distance charges to call the number. In cases where people don't have unlimited voice minutes (other cell companies), applicable daytime/airtime minutes do get used up, but there is still no charge for the actual long distance.
I have read that customers of Chatr have had problems making toll free calls. I read this back at a time when i was trying Chatr out and I can say that those calls worked fine for me. Toll free calls also work fine for me at Public Mobile.
If Public Mobile is giving you message saying that you need a long distance add-on, that is either a system error, or the number isn't really toll free. There are some area codes that may look a to be toll free but aren't (similar numbering). There are also some toll free phone numbers that can only be accessed from specific countries (example: some can only be called from the U.S.).
Here's a Wikipedia article about toll free numbers. https://en.wikipedia.org/wiki/Toll-free_telephone_numbers_in_the_North_American_Numbering_Plan
