Is there an app or something that I can make calls from the US to Canada for free?

Is there an app where I can call Canada from the US for free? I have an iPhone and my phone is shut off at the moment so I have to use an app for texting, but don't know of any that I can call from. I really need to make a call to a friend who is in Canada.

Try skype

Try the Magic Jack
http://www.magicjack.com/plus-v05/