One of the most in-demand features of Internet calling is mobile VoIP. Mobile VoIP allows mobile devices to send and receive Internet calls. Internet calls can be made over any IP network, so anyone who downloads a mobile IP app can send calls over any WiFi, 3G, or 4G data network.
Rather than use your wireless minutes, mobile VoIP uses your data plan to make calls. This translates to lower per minute rates than your cellular service provider.