A free program for Android, by Dmitry Nikolskiy.

Talkie is a new generation communication app based on the Wi-Fi connection. It works like a regular phone, but you can call and send messages over Wi-Fi. This means you can call and send files to your friends and family at home or on the road, even if you’re in a place with weak signal

This communication app was developed to solve the problems of communication in the era of the Internet and the mobile phone. The main idea is that if you can’t find a Wi-Fi hotspot, you can create one.