Voice quality of interconnected PCS, Japanese cellular, and public switched telephone networks

The non-linear nature of low-rate parametric speech coding has made it necessary to resort to formal subjective assessments for quantifying end-to-end voice quality of interconnected networks. At the same time, the rapid growth of cellular communications has highlighted the need to characterize transmission quality when cellular terminals are attached at the access or termination nodes of switched networks. In the paper the voice quality of interconnected North-American and Japanese digital cellular systems over public transmission facilities is quantified. From these assessments it is concluded that cellular networks using 8 kbit/s or 6.4 kbit/s VSELP may meet end-to-end quantization distortion criteria when interconnected with the switched network