According to one embodiment, a communication system includes an analog voice bridge coupling one secure network domain to another. The analog voice bridge includes two codecs that are each coupled to a secure network domain and to each other through an analog voice line. One codec decapsulates an analog voice signal from a digital voice stream received from a terminal, and transmits the analog voice signal to the other codec through the analog voice line. The other codec encapsulate the analog voice signal in another digital voice stream and transmit the encapsulated digital voice stream to another terminal coupled through the other secure network domain. The analog voice line conveys the analog voice signal from the first codec to the second codec while restricting communication of the digital packet stream between the two secure network domains.