WCF - Send callback without a Clientcall

I use a DuplexChannelFactory to send callbacks to my clients. I would like to send those callbacks before a client call was made.

In other words the moment a Channel is opened via DuplexChannelFactory.CreateChannel() I wish to send a Callback to the client that ju开发者_运维问答st opened this channel.

Any Ideas?

You can't because you don't have callback channel available in the service. Client must be the one who initiate communication. Moreover I'm almost sure (I didn't checked it) that CreateChannel doesn't open the connection but the first client call does.