The application places an audio/video call to the designated target, after initializing platform and endpoints. After the call is connected, the application waits for the AudioVideoFlowto become active (when the value of its Stateproperty is Active), and then attaches a ToneControllerand registers a handler for an event that is raised when a tone is received. After a tone is received the platform is shut down normally.

• Basic audio/video call placement
  
  
• Platform an endpoint initialization
  
  
• Relationship of ToneControllerto AudioVideoFlow
  
  
• Using ToneControllerto receive tones from the remote side
  
  

• Microsoft Office Communications Server 2007 R2.
  
  
• Two users capable of sending and receiving audio calls.
  
  
• The credentials for each user, and a client capable of signing in to Office Communications Server.
  
  
• A client signed in to Office Communications Server.
  
  

1. Replace the credentials in the variables at the beginning of the code sample with the credentials and server of the users from your Office Communications Server topology.
   
   
2. Substitute the address of the called user in the code sample with the address of a valid, currently signed-in user capable of receiving audio calls.
   
   
3. Open the project in Microsoft Visual Studio, and then press F5.