Over-the-top communications currently represent the largest threat to mobile operator revenues, according to a latest report from ARCchart. Prominent examples of OTT services such as Skype and WhatsApp have had a direct impact on the mobile industry's profitability and are placing pressure on operators at a time when they are compelled to build expensive new 4G networks. ARCchart forecasts that OTT services will account for 8 per cent of all voice traffic carried over mobile networks by 2016. Release