You can communicate with your remote partner using voice and text chats.
There are two buttons on the title bar: Send message... and Speak...
If you click the : Send message..., you'll see a chat window. Here you can send the text messages to your partners.
If you click the Speak... button, you'll see a small window with the Stop button on it. Now you can talk to your partner in real time. If you click the Stop button, the application will stop listening to your voice through the microphone.
Important: in order for your partner to be able to answer you, in his Distant Desktop he must click the button, and select "Speak..." or "Chat..." item from the dropdown menu. The button is located on the title bar.