With google voice can you call for free in US and Canada?

When in US, google voice allows free calling to canadian landline and cell phone?

https://www.google.com/voice/rates

Is that right, no fees at all?

So if you have a data plan in US you dont really need international calling plan to call canada?

Does the google voice app drains a lot of battery?

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Not to confuse you more, but now on Android phones, there are now two options with Google Voice.
1) In the phone app, it is free to call NA but you will use your local airtime. Make sure you have unlimited or don't go over.
2) In the hangout app, it acts as Skype and uses VoIP to make phone calls. This doesn't eat the airtime but you need fast & stable wifi/data to have good call quality. 

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yes, but people in Canada can't call you if you are in USA
use Fongo APP. you Can call Canada
and people in Canada can call your Fongo #

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Anyone in the world can now install the Hangouts Dialer add-on to Google Hangouts and call phone numbers in the U.S. and Canada for free (rest of the world is mostly 1 cent per minute).

If you have a Google Voice number (U.S. only currently), you can link it to Hangouts to receive incoming phone calls. You can also send and receive SMS text messages for free via your GV number.

It works very well over WiFi, not so great over a cellular data connection because audio streaming suffers from frequent delays of a few seconds.

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For those with a google voice number, it works on the computer as well.
https://support.google.com/chat/answer/187936?hl=en