I just switched to T-Mobile for the .20 calls in countries I am visiting and unlimited text and data.

However, I have been told that T-Mobile will not work on the Royal Princess. It is imperative that I am able to call a land line with a cell phone from the ship to keep in touch with my aging mother who doesn't have wifi/computer/etc. Has anyone tried to call with T-Mobile on the royal? why would it work on other princess ships and not the royal?