New Delhi-based Bharti Airtel and Navi Mumbai headquartered Reliance Jio Infocomm (RJio) are in advanced stages of testing Voice over Wi-Fi (VoWi-Fi) services, a technology that keeps users connected even without a mobile signal. This move will enable telecom companies to take on over-the-top players such as Skype, WhatsApp, Hike, Facebook...