We use Magic jack as our home phone number in Canada. We have a Rogers rocket 4G data hub supplying our internet access and it works just fine. We use the MJ Plus where we don't have to have it connected to a computer and hook it directly to the Rocket Hub. When we travel south for the winter we use to take the MJ Plus and use it from our lap top when we connected to WiFi (ie) Mc Donalds, Lowes, Campsite's etc. We now just use the App on my wife's Ipad to call and answer our phone anywhere we have WiFi access. We can now leave the MJ at home for 911 calls if our house (babysitters)need it. The trick is to have a designated MJ phone number ($10.00)/yr extra and register the number on the Apple app when installing it. This seems to eliminate most of the MJ issues re lag time delays and call dropping. This way we take our home number with us where ever we are and don't miss any calls. MJ also emails our voice messages, so if the WiFi is poor we can still check our messages to see who called and why. Family can get us anywhere and it's just a local call for them, no long distance charges.
Like most other snowbirds we also carry a cell phone for on road emergency use. We have an unlocked phone and use a pay as you go Global travel G3 wireless simm card (no roaming fees) It's only 9 cents a minute local/long distance and data is only 9 cents/MB anywhere in US. In Canada it's 25 cents/minute. So if there is no wifi available I take the Simm card out of the phone and put it in the Ipad so my wife can check emails and make lenthy MJ calls to our daughters from her Ipad App. We find that the MB usage for making MJ calls on the Ipad is on average 1-2 cents per minute.
Hope I wasn't to long winded, getting eager to head south.