I am having vonage and have tried their 800 service. It took about 5 minutes for it to start working and didn't had any problems.
I get tons and tons of features on the phone line and "unlimited" calling to USA & Canada (I think they also have mexico, but never used it). In addition what I loved is their voicemail feature. If someone calls you and leaves a message, you have a choice where vonage will actually email you the voicemail via email and you can listen it or store it forever on your computer (trust me.. it can be very useful for certain calls).
In addition, vonage has great international rates and best of all, if you travel anywhere (in the "world") you can just take your vonage adaptor with you and plug it to "any" high speed connection (I think vonage needs about 90kb to work) and you can still get unlimited calling to usa and canada for free.
Best way to figure out if vonage will give you 800# in canada or not, is by calling them, here is there toll free # 1-866-243-4357
Hope this helps.