Hi all, I have made a WCF service which is defined like this: [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Multiple)] binding is done using netTcpBinding. We support 50+ clients that call the server from time to time. Each client opens a channel using channelfactory once it is loaded and uses that channel for all calls (creates the channel and proxy only once). we have built a small load tester that imitates the client by calling the server by 50 different threads at once (using 50 different channels). when we run this tester, after the 10th client tries to connect, all other client fail connecting. We have set throttling to 100. My questions are: 1. is it correct for each client to create a channel and use it through the client life time? or, do i need to use a using statement for each call to the server (create and distroy a new channel for each call). 2. does the service have a limit of channel connections to it? other then throttling? thanks alot, Guy.