I am visiting Vancouver this weekend and called ahead to a hotel I was staying at. I am under the impression that Canadian numbers are considered international if you are using an American phone. To my surprise, the international dialing code for the number I called is the same as the US and the number format is also identical (xxx-xxx-xxxx). Is calling / texting Canadian cell numbers considered international? Also, if I use my American phone in Canada, are there roaming charges?

I have ATT as my provider.