iPhones purchased using AT&T installment plans are an example of when they are not unlocked. Canadian carriers may have a similar restriction…unless purchased in full upfront from Apple in what used to be listed as the unlocked version….in the US that option now just says you’ll choose your carrier later. Not knowing what method you used to purchase is why I said if it’s unlocked. Carriers have varying sim lock policies. Verizon is the only one I know for sure that doesn’t sim lock anymore although they used to for the first 90 days I believe. At any rate…without knowing what carriers may do in Canada and not knowing which option you purchased using it was safer to say as long as it’s unlocked.