Charged for Magic Jack international calls?

If they are routed over cellular.

To avoid it, turn off cellular while making the calls out of the country.

I was doing a little more search over the forums and saw an old post that it was against the Terms of Service (TOS), so I'm not sure about doing it, unless rules have changed recently. I figured if you turn off cellular data on the phone and just use your wireless network as you said, it could be done, but I got an old Android phone and can't see where I can turn off the cellular service, and if I switch to airplane mode that disables both cellular and the wireless service, which the app would need to work. So maybe back to the old wired connection.

You can turn on airplane mode then turn wifi back to on.  This will use your wifi and avoid any cellular charges.