VoIP conference room app

I intend to create a voice conference room for making conference calls, but I don't have much experience with it. On a forum I got this link:
(since links are not allowed please google: voip sip sdk conference room)
This is the conference room application of the Ozeki VoIP SIP SDK. It seems fair, but I would like to extend my knowledge with some extra ideas from you, fellow developers. Can you help me?