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How to get free phone calls with smartphone apps
Notify your friends in advance that you're about to use an app to communicate with each other.
Tell them to download the app, which will be explained later in this article.
If your phone has a data limit, check if you still have at least 500 mb of internet data.
You might want to use a free public wifi if you have no data (or have little data left). On your phone, launch the respective app store.