You can't use SkypeIn in Canada as of yet, unless you want a number from US or European country.
I use it mostly on my Cell phone, Nokia N95 via Fring. I talk to my family overseas in Europe, Middle East, Pakistan and USA. Skype has an unlimited calling plan for select European countries and US. There's also a $3 North America wide plan.
Very decent audio/video quality on slow connections too. Found this out much to me pleasure on my recent overseas trip.