All Voice over Internet Protocol (VoIP) services like Whatsapp, Viber, Skype and FaceTime that allow free calling via an internet connection, are banned in the UAE. Note, their messaging platforms are permissible.
Botim is the only VoIP service that is legal in Dubai. It is a paid service and is integrated with your SIM card. It costs AED 50/Month and provides unlimited voice and video calls. To know more about Botim head here