Make TAPI or IVR or Telephone answering etc

hello
i want to make software (Application) telephone answering ?
caller ID telephone?
fax with telephone?
Play sound? And sound recordings?
If the client. Press the call button. I will identify and reaction be?

how can i do it?
i see this website . But I do not understand

http://www.kaed.com
http://www.codeproject.com/Articles/26751/IVR-applications-based-on-Voicent-Gateway-C-Sample
http://www.codeproject.com/Articles/26854/IVR-applications-based-on-Voicent-Gateway-Java-Sam
http://www.codeproject.com/Articles/14034/Answering-machine-TAPI-2-1