I am using an Iphone with iOS 8, and just installed the latest version of WhatsApp, which allows for voice calls from inside the app. Everything is fine... except that I don't see where are the calls logged. They don't appear in the calls log of the Phone app, nor there's any icon in that person's chat history. Where are they?
Answering my own question: there's a new tab in Whatsapp called "Recent", which I hadn't paid attention to. It's the second one from the left, and it has the log of your recent Whatsapp voice calls.