From the Indiegogo page: "You can do this via WiFi (in your hotel or a cafe) or via a Data SIM card. The Roam comes with a Data SIM card where you can pre-purchase data. Alternatively you can use a local SIM card when you arrive at your destination." So it's a global sim from Strone, a local sim or WiFi.

To make a call you need to have our app installed and be able to connect to the internet. The Roam will ship with an international data SIM where you can pre-purchase data to connect to the internet. If you find a cheaper local data plan then you can use that as well.

And... for the calling, it looks like you do that from the app too, when you're in foreign parts.

Matthew from Strone here. Yes - while your SIM is in the Roam all incoming & outgoing calls and SMS flow through the Strone app. Basically the Strone acts as your messaging and calling apps on your phone for that SIM in the Roam.