Help with Media Project

I am working on a media project involving a automated phone service as a musical device.

Basically, I want to have an answering service where the outgoing message cycles randomly through a series of pre-recorded clips so that when multiple people call at the same time, they will (may) receive different clips.

If anybody understands the intention and can help me with some of the commands, I would be very grateful.

Any advice or design hierarchy would be great too.