I’m using a sample program providing by Ozeki VoIP SIP SDK to develop chat program. I can create effective VoIP solution with it eg: text, audio and video chat program. It doesn’t require days to configure or exhausting background work for support audio and video codecs.
You can use different developer environment such as: Microsoft Visual Studio 2010, Microsoft .Net Framework 3.5 or 4.0, Flash builder 4.5 or other equivalent IDE or Flash player 10+.
Plus, its support team is really fast and helpful!
If you would like to try it, you can check the site here http://www.voip-sip-sdk.com/p_96-win...-ivr-voip.html