[ServiceContract(Namespace = "http://schemas.winfxitalia.com/Chat", CallbackContract = typeof(IChat))]
public interface IChat
{
    [OperationContract(IsOneWay = true)]
    void Login(string name);

    [OperationContract(IsOneWay = true)]
    void Logout(string name);

    [OperationContract(IsOneWay = true)]
    void Chat(string name, string message);
}

void IChat.Login(string name)
{
    Console.WriteLine("{0} has logged in", name);
}

void IChat.Logout(string name)
{
    Console.WriteLine("{0} has logged out", name);
}

void IChat.Chat(string name, string message)
{
    Console.WriteLine("{0}: {1}", name, message);
}

<system.serviceModel>
  <client>
    <endpoint name="ChatService"
      address="net.p2p://winfxitalia/Chat"
      binding="netPeerTcpBinding"
      bindingConfiguration="chatBinding"
      contract="PeerChat.IChat">
    </endpoint>
  </client>
  <bindings>
    <netPeerTcpBinding>
      <binding name="chatBinding" port="0">
        <security mode="None" />
        <resolver mode="Pnrp" />
      </binding>
    </netPeerTcpBinding>
  </bindings>
</system.serviceModel>

// Creo il factory per la creazione del canale
// Utilizza la classe stessa come implementazione del callback
DuplexChannelFactory<IChatChannel> factory = new DuplexChannelFactory<IChatChannel>(this, "ChatService");
// Creo il canale
chatChannel = factory.CreateChannel();
// Apro il canale di comunicazione
chatChannel.Open();

Console.Write("Insert user name: ");
string userName = Console.ReadLine();

// Inizio lo scambio di messaggi
chatChannel.Login(userName);

string msg;
while ((msg = Console.ReadLine()).Length > 0)
{
    chatChannel.Chat(userName, msg);
}

chatChannel.Logout(userName);