If you have laid your hands on The BlackBerry Priv, you will discover that it supports Wi-Fi calling, which allows you to make and receive calls over Wi-Fi, even without mobile network coverage.
How to enable Wi-Fi calling on your BlackBerry Priv
Open the Settings app.
Tap on the Wi-Fi Calling Menu section
Tap More in the Wireless & networks section.
Set the Wi-Fi Calling toggle switch to On.
Go to Wi-Fi Calling Preferences -> Connection Preferences to set your Wi-Fi Calling Preference.
You have a choice between:
Wi-Fi preferred – make Wi-Fi calls, even when you have a mobile network signal
Wi-Fi only – only make calls via Wi-Fi calling
Cellular network preferred – only use Wi-Fi calling when you have no cellular signal
Once you have done that, you’re set to go. Note that your network has to support Wi-Fi calling for it to work.