Asterisk (www.asterisk.org), is a piece of extremely powerful VoIP/PBX software. It can bridge just about any codec (u/aLaw, G.729, G.xxx, GSM) and protocol (SIP, SCCP, H323, and it's own IAX). Plus it's got a ton of cool features and is extensible. The only downside is that for maximum power, you must use the C API. For some people, this means low productivity. For others, it means forgetting about having great flexibility and power.

I like C#, and I want to write most of my code in C#. But, I'm also going to be writing a lot of code for Asterisk. So, I'm doing the only sensible thing: Embed Mono (www.go-mono.com) into Asterisk and load my .NET assemblies from there, while exposing the complete Asterisk C API to my .NET applications. (In other words, much more than just spawning a new process and passing args and reading stdout).

Well, after spending 2 days trying to get Mono to work and my code to link to it, I finally got things working (without formatting and laying down Fedora Core 2!). Nothing much yet, but I got a sample program to be loaded into the Asterisk process, and I executed by dialing an extension. Now I just need to complete the API, enhance the loader, and do everything else, and I'll have a very solid project.

If you use Asterisk and would like to write with C#, contact me (mgg @ this domain .com). I'm also in #asterisk on irc.freenode.org as AgiNamu.

Or, if you like Microsoft and .NET, but want to get into VoIP, drop me a line. I haven't seen any real solutions that compete against Asterisk for Win32 (or Win64).