Recently a train on the North Atlanta District set off a "Detector Alarm"...
The crew was not able to make out the type or location within the train as the detectors transmitting details were "walked on" by other radio traffic in the area. The dispatcher reminded the crew that they can tone up a detector for play back "#001" and the detector will rebroadcast its last transmission. Even I had forgotten about that detector feature as it is not that often that crews need to use it.
Also detector help desk can be talked to and info confirmed.