Carrier change

This is one of the several issues that one encounters when purchasing an iPhone in a country they do not intend to use it in. One of the others is that your warranty is only valid in Canada as well. Contact Apple Support with the serial number and they should be able to tell you what carrier it is locked to. Then you will need to contact the carrier and see if they provide unlocking services and if you qualify. Getting the device unlocked is not guaranteed, and yes, they could charge you for it.

You must contact the carrier the phone is locked to and ask about their unlocking policy. They are the only ones who can unlock it.