I am sailing on the Allure in April with my husband, son, and my son's best friend. We have two separate cabins. So I think I was naïve and under the impression that if I did not purchase WIFI for all of us we would not be able to text one another one the ship. But reading now I am starting to get the impression we would have been able to contact one another via the RC app when we are connected to the ship's WiFi. Is that accurate? Or do we need to purchase internet to reliably text each other?