Know this is an old post but thought Id share the experience I just had with CID on an X16.Customer reported that CID was sparodic to non existent after a year of working fine.Did the usual, test calls on each trunk, CID was ok from the phone co(Cox Cable), rebooted system, etc,etc,etc.Finally talked to an engineer and explained my problem. His first question was "Is system plugged into a surge protector" I said yes as well as the LEC.He told me to plug directly into wall.I was a bit skeptical but tried it and he was correct.CID worked fine after that.Dont think Ill forget this one.