Quality of service for IP voice services - is it necessary?

New services come at cost to the Internet community, therefore determining the needed level of QoS for the services is important. This due to the fact that guaranteeing quality demands extra functionality and extra cost for equipment in the network. We have chosen voice transmission over IP network as a candidate service for the study of QoS issues. We wanted to see what is the difference in perceived quality of service in following cases: a network with conventional forwarding and a similar network using a layer 3 switching (IP-switching). We present measurements with a commercial embedded microprocessor system and a public domain software in a general purpose computer. From experiences we can say that the present general purpose computer architecture is no means optimal for providing controlled quality of service for a real-time communication. We conclude that routers offering real-time services need prioritized traffic handling.