As David says, use your CVP Studio and build an application. There's a Recording element that is very useful but you will have to deal with getting the recording up to your redundant Media Stores.
I wrote a custom Action Element to FTP to a FTP server and used it twice in a row.
You have to deal with quite a few different conditions in this application - you will get the basics working in an a day and then spend two weeks refining it.
One thing to be aware of - make a directory on your Media Store for the recordings and set the content expiration really low - say 10 mins. Otherwise, your new recording may be not be played because what is in the gateway cache is not stale.
On the call inbound side, you would be looking at an ICM global variable that controls whether the message should be played - then a simple microapp to play - using a well known WAV filename.
The CVP application sets this global variable after checking the caller's pin.
It's all fine. We have exactly this application and port it to customer's who require it.
I reckon it will take three weeks to get a production-ready application, so don't quote too low. ;-)
Regards,
Geoff
