How to use VOIP on Android phones?
Use VOIP on Android phones
To use VOIP on Android phones, you will need access to the internet. The connection needs to be a fast connection using a direct connection to a WiFi network, or by using a 3G, 4G, or 5G mobile data connection via your phone carrier.
Voice Over Internet Protocol (VOIP) is a process of making voice calls using the internet instead of using standard telephone lines. In most cases, all you need is an app on your Android phone or tablet to make this work.
VOIP on Android phone or tablet requires you to have an app installed that facilitates the connection. Some of the best apps that are free, very popular, and also work well are Messenger, WhatsApp, Skype, and Line. Both of these apps will allow you to call another user of the same app for free, anywhere in the world. But the call must be between the same app such as Messenger to Messenger, Line to Line, etc.
Skype will also allow you to call from your phone to any cell phone or land line in the world for an additional fee. They have an annual fee that allows for unlimited calls instead of paying by the minute.
There are many other apps that will facilitate VOIP calls such as WhatsApp, Facebook Messenger, Telegram, and many others. The people at both ends of the call must be using the same app. Currently, none of the VOIP apps will cross over to another app.
Here is more information about how to make video calls – Video Chat on Android Phones