Hi, so just find the ETP, although from your post signature it would seem you are in a multi tenant building. You just need to locate where the inbound line from the comms room distribution frame connects to the apartment wiring, the most likely place is in the now disused alarm panel, but it could be another socket, once disconnected (ie phones loose battery and dailtone) then it should be safe to connect your ATA, but first confirm no battery etc. I wont be in Welly in the near future, otherwise I would offer to do it.
Cyril