Phone Tree Faxing Solutions?

ptb asks: "Since I am sure that someone in the Slashdot community at large has developed a solution to this question I figured I would ask. I am trying to get the company I work for to abandon a fax solution vendor for an in-house developed solution. I've managed to implement hylafax and faxing PDFs from a Web page works flawlessly. (I am embarrassed I didn't have to do more, but hey... ;) My question is: has anyone ever developed a Phone Tree under Unix? What I'm hoping to do is have customers call a number, have my Linux box answer and the customer presses '1' to order a document or '2' to order an index... You get the idea. If they order document '23532' then my perl script will fax them the doc. I've found ACS and Quicknet but I suspect that someone has traveled this road before me. Any suggestions?"