Voice over IP 15. Voice over IP: Speech Transmission over Packet Networks
Jan Skoglund, Ermin Kozica, J. Linden, Roar Hagen, Willem Bastiaan Kleijn · 2008
The emergence of packet networks for both data and voice traffic has introduced new challenges for speech transmission designs that differ significantly from those encountered and handled in traditional circuit-switched telephone networks, such as the public switched telephone network (PSTN). In this chapter, we present the many aspects that affect speech quality in a voice over IP (VoIP) conversation. We also present design techniques for coding systems that aim to overcome the deficiencies of the packet channel. By properly utilizing speech codecs tailored for packet networks, VoIP can in fact produce a quality higher than that possible with PSTN.