Voice coding conversion circuit between office exchange and ISDN keyphone system

摘要

A circuit for converting a voice coding mode of a basic rate interfacing (BRI) card in an ISDN (Integrated Service Digital Network) keyphone system according to a voice coding mode of an office exchange. A PCM (Pulse Code Modulation) coding conversion circuit between an ISDN keyphone system and an office exchange, including an A/mu-Law converter for converting the voice coding mode of the PCM data output from the ISDN keyphone system to an A-Law voice coding mode or a mu-Law voice coding mode according to a coding mode of the office exchange and for converting the voice coding mode of the PCM data input to the ISDN keyphone system to an A-Law voice coding mode or a mu-Law voice coding mode according to a coding mode of the ISDN or keyphone system, in response to a control signal output from a central processing unit so that a voice coding mode of the office exchange is matched to a voice coding mode of the ISDN keyphone system.