Whatsapp no use internet

WhatsApp users are plural using video calls as well as voice calls on the platform. Consideration, calls through WhatsApp does not cost money, compared to calling credit through mobile. However, the WhatsApp call service uses Internet data.
Well, not long ago, Rwandan students, Doedate Mugenzi found a way for WhatsApp users can use internet calls.

To use WhatsApp communication call without internet, Mugenzi must enter the caller and recipient number in WhatsApp. He uses WhatsApp as a platform to connect two people.
Mugenzi's computer system combines optical physics, mobile gadget communication techniques and networking principles. Mugenzi believes this prototype can benefit both consumers and service providers. The prototype system allows WhatsApp users to directly call mobile phone numbers.