Voice over IP: the challenges behind the vision

If the Internet were to displace the telephone network for voice communication, it must be capable of providing the same level of service quality as the telephone network. However, this is not straightforward since the Internet was not designed with voice communication in mind. Voice packets transmitted over the Internet incur loss and delay jitter. While certain measures can be taken at the application layer to overcome these problems (such as loss concealment and adaptive playout), their effectiveness is limited to only certain ranges of network conditions. This paper explores some of the issues underlying packet networks that make up the Internet, with a particular focus on the Internet backbones and wireless LANs.