Modification to a IVR

I have a working freepbx, all is good. However I need to create a IVR with a call route striaght to voicemail that will give the caller a unique ref no (doesnt matter if its numeric or alpha) and then save the ref with the voice mail

This is so that I can have an automated call logger for our helpdesk that non tech people can register calls and just attach the audio file so there is no miscommunication. as this is a huge problem for us.

Im not a software delevloper and my linux skills are basic (MSCE what do u expect) however im moving our platforms to linux and slowly learning (slowly due to the fact linux rarely **** up)

Many thanks up front