Click To Call

We want to start offer a service that will put a "Call Me" button. When the customer that is brousing the website clicks on this button a small window will open. asking the customer to enter their name,email and phone number. Or the customer can call from his computer using a small JAVA or whatever applet and call the other party using a headset. It could be either computer to computer call .. or computer to phone call or phone to phone call. Customer does not need to be logged in to make the call but the other party needs to so the customer will know they are online and waiting for a call. Dynamically once the call is made the online button should change to busy while on a call. Or if the party receiving the call is not logged in then the button should say offline. When they hit submit the system will call the owner of the "Call Me" button. We have a phone switch for the calls and will like to use asterisk for the platform. Thanks Ed