Hello!

I'd like to create little system such that:
1. user from mobile phone calls server
2. server recognizes in real time what user says
3. server answers to the user on mobile phone with mp3 files
At this moment my idea is to:
1. have Skype on mobile phone
2. call Skype on server
3. redirect speech from/to Sphinx4 ASR (automatic speech recognition) with the use of C# server application
4. recognize it on Sphinx4 (Java)
However, I think it can be done in easier way, i.e. with IVR (interactive voice response). Some of IVRs are based on DTMF (I don't need DTMF) and other on ASR (which I need). And I've got two questions. Are there any freeware, opensource IVR software systems? How can I benefit from using Digium cards or/and Asterisk software?

Greetings!