I have come upon is once in that past and it depends on how new the elevator is because in a lot of the new ones I was told that they run extra cat5e cables in the umbilical to the elevator so maybe the building engineer might be able to give you more info on that and yea axis camera are great for this situation
so I have a customer that has an older spectra III ptz camera that he wants me to hook to his digital watch dog dvr but it has the tx+/tx- and rx+/rx- on the camera side and on the dvr side all it has is the rs 485 mot sure if it evan going to work just thought I would throw it out there and see if there is anyone that has a insight to these older cameras