C#

[ClassInterface(ClassInterfaceType.None)]
[ComSourceInterfaces( typeof(IPhoneControlXEvents) )]
public class PhoneControlX : MarshalByRefObject, IPhoneControlX
{
  public event PhoneControlXEventHandler OnCallOffered;
  ...
  public bool Connect()
  {
    BinaryServerFormatterSinkProvider serverProvider = new BinaryServerFormatterSinkProvider();   
    BinaryClientFormatterSinkProvider clientProvider = new BinaryClientFormatterSinkProvider();   
    serverProvider.TypeFilterLevel = TypeFilterLevel.Full;
    IDictionary props = new Hashtable();     
    props["name"] = "RemotingClient";   
    props["port"] = 0;   
    _HttpChannel = new HttpChannel(props, clientProvider, serverProvider);   
    ChannelServices.RegisterChannel(_HttpChannel);

    _PhoneControlServer = (IPhoneControlServer) Activator.GetObject(typeof IPhoneControlServer),remotingURI);
    
    _PhoneControlServer.RegisterCallback(this);
  }

  public void PhoneControlCallbackEventHandler(object sender, IPhoneControlEventArgs e)
  {
    //this event handler is never invoked when PhoneControlX is instantiated by VB6 client.
    PhoneControlXEventHandler xe = new PhoneControlXEventHandler(CauseCallOffered);
    AsyncCallback acbCauseCallOfferedComplete = new AsyncCallback(CauseCallOfferedComplete);
    xe.BeginInvoke(e,acbCauseCallOfferedComplete,PhoneControlOperation.CallOffered);
  }
}

public class PhoneControlServer : MarshalByRefObject, IPhoneControlServer
{
  public event PhoneControlEventHandler PhoneControlCallback;
  ...
  public void RegisterCallback(IPhoneControlX x)
  {
    this.PhoneControlCallback += new PhoneControlEventHandler(x.PhoneControlCallbackEventHandler);
  }
  ...
  public void CauseCallback(IPhoneControlEventArgs e)
  {
    if(this.PhoneControlCallback != null)
      PhoneControlCallback(this,e);
  }
}