The most awaited feature from instant messaging application Whatsapp has been active from the past few days. I have been using this feature to call people in my Whatsapp contact list. This feature can be activated only when a person already who has feature calls you device.However i have been experiencing some problem. When we are calling someone we don't hear the phone ringing. So, we cant be sure if the receiver is not taking the call or their device is not connected to a network or there is any other problem with the receivers device. We need to have a minimum network speed of 3 Mbps on both the devices to avoid lag. However i later found out that even though the devices had the required network speed, there was lag in the voice messages which could be quite annoying. Some user who have latest version of Whatapp are unable to view the call button, even though they have been called by a person who already has this feature. How to activate Whatsapp calling featur...