How much will it cost me to use messenger without wifi if I am calling Canada from Australia?

Using Messenger without Wi-Fi means you'll rely on mobile data, which can incur charges based on your mobile plan. The cost will depend on your data usage during the call, as Messenger uses data to transmit voice and video. Check with your mobile provider for their rates on international data usage, as they can vary significantly. To avoid unexpected charges, consider using a Wi-Fi connection whenever possible.