create an application to make a call using phone line and play a sound after answering the call

Hello Everybody I want to create an application to make a call using phone line and play a sound after answering the call How it works ? 1. The app will visit an static URL and get two variables from this URL "phone number & sound file url" 2. The app will download the sound file to the phone 3. Call the previous phone number and after answering will play the sound 4. After finishing the sound playing, The call will finish 5. After that, The app will send callback to another static URL with 3 variables ( call status if successful or number busy or number is out and the phone number and url of played sound ) We will talk about some informations about the app like "when the app try to visit the first url to get the variables ?" Thanks a lot