The Fork function creates a forked copy of the current message with its request URI field set to the supplied URI string.
void Fork( string uri );
Call this method for each URI you are forking the message to. Before calling this method, BeginFork must be called to initialize the forking operation for this message. The forked messages are sent collectively with a subsequent call to EndFork.
If you are forwarding to only one destination, ProxyRequest should be called instead. A message cannot be forked if it has a strict (fixed) route. Messages with a strict route have the "Route" header present.
An error is generated if Fork is called without a previous open call to BeginFork.
Although Microsoft Lync Server 2010 APIs permit a request to be forked within an already established session, you should not do so. Forking, say, an ACK request (or any other request with route headers) will confuse endpoints that were not already part of the conversation.