I would like to develop my own IVR application. I wish to build an IVR system in C# but to tell the truth I am newbie. After searching on the Internet I found a site (www.voip-sip-sdk.com/p_117-c-harp-dtmf-ivr-voip.html). The sample programs are based on an SDK which is called Ozeki VoIP SIP SDK and they are in C#. What are the pitfalls of the IVR systems?What should I pay attention in during the development?