Rugged tamper resistant substations with a unique design to protect the speaker/microphone, call button and internal electronics from external abuse. The stations are ideal for jail cells, sally ports, parking garages and other security applications. The speaker provides good microphone sensitivity and excellent voice quality. It provides clear, hands-free, two-way communication when called. The stations provides a balanced audio line with no hum and noise, and circuitry for line supervision. The stations will operate on the STENTOFON 9200, 9400 and 9600 systems.