Help with a project (automator, phone, skype)

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.

From the research I have conducted, I understand that utilizing the Skype API you can write a script in automator to affect certain aspects of the program although I'm not sure if changing the outgoing message would affect the integrity of the program.

If anybody can recommend any possible way of achieving these results I would be very grateful.