In a previous post I presented you a simple to use SIP proxy that can be installed even by beginners on any Windows machine. Another very easy to use SIP Server is coming from brekeke.
Called OnDO SIP Server the product is a SIP Registrar and Proxy Server that registers and authenticates users, and routes calls between user agents. Although the product has by far less features than Asterisk, is still an interesting option for VoIP beginners, especially because OnDO SIP Server is free for personal and educational use.
You can download the software from http://www.brekeke.com/ and in a few minutes you’ll be your own VoIP provider.