Tel. Directory Assistance with Asterisks (Voice Recognition)

Hello, I would like to start a fully automated voice recognition based service to get telephone numbers in a German speaking country. I have AT&T natural voices licensed to generate voice-files by text-input, but I don't have the other part developed or licensed yet, that I can convert speech to text. Especially I have no idea how to do that in telephony applications or in a Asterisks enviroment. I would like from you that you develop based on our database of the official phonebook a directory assistance (telephone operator) where you call a telephone number like 11833 and then the service picks up and plays a message "To look up a telephone number please speak the last name now..." .... "Thank you, we have recognized 'Meyer' as last name, is that correct? Please say yes or no after the beep" ... "Please say the first name after the beep" ... " Please say the city where the person is living" ... etc. etc.. The basic system should be all based on Asterisks for example and Digium 4x E1 cards I have available and bought already, where you should tell me me what kind of server I must buy which can handle up to 4x E1?! The budget for that service in V1.0 should be around 1500,- USD or less, where I will have many many future requests then if the service is once up and running... Can you do something like that?