TCP Server Needed

This project may be a little hard to understand so let me know if you have any questions. I need a main tcp (or other protocol) server that will run on my own dedicated server with open ports. Then what happens is clients will connect to it when they go online - very similar to an instant messenger system. When two users want to connect to either other for either chat or file transfer, I need the server to create a connection between the two so they can communicate with each other. But I need to find a way where they can connect without their data going through my dedicated server. The reason I am trying to do this rather than having one connect directly to the other is because of routers and ports.? If I were to just give one of the clients the other client's IP and port to connect with, then they could connect directly as long as there is no router. But if they have a router, a client can easily make an outgoing connection without worrying about port forwarding. So I need to know if this is possible. If it is not, then tell me an alternative that can help with this situation. Like how does AIM, MSN, etc. do this. I would even pay just for the knowledge if I can understand it. Please do me a favor and do not bid unless you know a solution. I would prefer some feedback other than just a bid or a reply saying you can do it. Be a little more descriptive.? I have a high feedback rating on here and am completely honest with everyone. Thanks