We use our magic jack in SXM. It plugs in to your computer and if your computer has a speaker, you don't need a phone. We have used ours that way or with a cheap "old style" corded phone we bought at CostULess. Agree that you need a good signal for it to work properly.
Again like someone said, depends on wifi. I called from room at Atrium and not so good , then called from royal Palm and the connection was awesome!!!! Keep the phone on airplane mode and it will ask to accept your contacts and you are good to go to US and Canada. The only problem is your phone number is not the number that shows up on other phone.