any open source instant messenger?

Question

I need to develop an instant messenger (like MSN Messagner, but only simple and basic function is fine), based on .Net (C#). I want to integrate the instant messenger with my current web site user. I want to know any open source (better C#) instant messenger to reference?

BTW: some of the users are using internal IP address (behind a gateway or proxy, like 10.10.xxx.xxx) -- so in this scenario two users can not use point to point message transfer if both of them are behind a gateway? And I think I have to develop a server which acts as an intermediate party to transfer message between two users, correct?

Answer 1

Pidgin is an open-source messenger. Not C# though (it's in C, actually)

Answer 2

I think you should take a look at XMPP. This is an open messaging protocol with many different client and server implementations.

It can also be run 'through' a webserver using BOSH.

Answer 3

Take a look at Jabber