Build Your Own Phone Tree?

ps asks: "A small club I belong to is looking to install an electronic phone tree. This is one of those boxes that you can call into, leave a message, and it will deliver that message to all the members of a group. There are ones commercially available for over $1000, but this seems like something that wouldn't be too difficult to build. I could imagine that either a sound card based system, or a specially designed microprocessor system would work. Has anyone built one of these before?"