App to app calling lets developers use VoIP technology to connect two smartphones via the internet.
This is the foundation of the most popular smartphone apps on the market today. Apps like Viber Messenger, WhatsApp, WeChat, and Line all use app to app calling to connect two devices with voice calls.
The power of VoIP
The technique takes advantage of VoIP technology to send voice data across an internet network: and because it is internet-based, apps like this can offer significant cost reductions and often even free calls.
Integrating app to app calling is much easier today than it has been in the past. App developers can take advantage of in app calling to keep users in their app before, during, and after the call.
There has also been a major change in the way businesses and app developers are adding voice calling to their apps, with app to app calling as an extra communication feature for their chat and instant messaging apps. Some apps like Line are also adding app to phone calling on top of this and letting users call regular landline and cellphone numbers from their app.