If both you and your contact are active on Dingtone, you have the option to push a button to talk. Your friend will immediately hear you and he can reply to you by pushing the same button in his Dingtone app, just like a real Walkie Talkie.
You can get the feature by tapping the following in an order: “More” >> “Advanced Features” >> “Walkie Talkie”. Choose your Dingtone friends to start real-time talking.
The Dingtone Walkie Talkie even works after you lock your phone.