Chances are high you don’t know if your Android phone supports Wi-Fi calling, and that is largely not your fault because your mobile service carrier probably doesn’t want you using it. The biggest gainer in Wi-Fi calling would be you (the consumer) and not your carrier who would rather charge you for both mobile data and voice calling.
You will be surprised to learn that most modern Android smartphone do support Wi-Fi calling, but you can only enjoy the feature if your carrier supports it. Even in developed countries like the U.S., it is only a handful of carriers who support this feature; T-Mobile being the biggest proponent though other like Sprint, AT&T, and Verizon do support it as well. Come to Africa; it is only a handful of carriers across the continent that supports this service.
How to enable Wi-Fi Calling natively on your Android phone
By default, this feature is disabled. To activate it, go to Settings menu and at the search bar, type in Wi-Fi calling. While you can take the long route of step-by-step procedure, using this shortcut will make it easier for you …read more
Read more here:: How to enable Wi-Fi Calling on your Android Phone