Can VoIP Live up to the QoS Standards of Traditional Wireline Telephony?

The PSTN is the ultimate benchmark for voice quality in communication networks. When the first VoIP solution was introduced in 1996, the Internet's audio transport capabilities were far below the benchmark set by public-network standards and therefore much lower per-forming than traditional telephony. Considering that Internet Telephony is constantly being promoted as the next killer application in Next Generation Networks and as the potential substitute for current telephony technologies, voice quality however needs to at least be equal to the level ISDN telephony provides at the moment. The following comparison of VoIP and traditional telephony QoS levels and their corresponding performance development revealed the following: QoS of Internet Telephony was intolerably low when first introduced, compared to the standards set by the traditional telephony. However, these shortcomings were largely factored out and optimised through numerous QoS enhancing methods, meaningful traffic engineering and network planning. This paper proves that QoS of today's VoIP solutions is fully satisfactory for end-users and that VoIP therefore constitutes a potential substitute for traditional telephony services.