For experiments, I created a simple \"Hello World\" WCF service and client using .NET 4.5 on VS2012. The server is hosted on a console application and use net.tcp binding. I
Look at this...
"Setting MaxTransferWindowSize
Reliable sessions in Windows Communication Foundation (WCF) use a transfer window to hold messages on the client and service. The configurable property MaxTransferWindowSize indicates how many messages the transfer window can hold.
On the sender, this indicates how many messages the transfer window can hold while waiting for acknowledgements; on the receiver it indicates how many messages to buffer for the service..."
Source "MSDN: Best Practices for Reliable Sessions": http://msdn.microsoft.com/en-us/library/ms733795.aspx