The NX-534E is a two-way audio (voice) communicator that may be added to a new or existing NX8 / NX8-E alarm panel. Once the alarm panel has communicated an alarm, the NX-534E will allow a monitoring service operator the ability to monitor a customer's premise for "listen-in" purposes or basic two-way voice communication. This procedure is controlled from the Central Station by use of a touch tone telephone.