This IEEE Std 823-1989 provides network planners with the methodology and models for calculating the transmission performance of connections made up of one channel or of two or more tandem channels. The performance parameters covered include connection loss, idle-circuit and quantisation noise, and talker echo path loss and delay. The methodology is given for determining the speech transmission performance and grade of service of a complete voice connection including the terminals (telephone sets), and evaluating the relative performance of alternative speech connections.<>