Network quality of service monitoring for IP telephony

This paper presents a non-intrusive method of determining network performance parameters for voice packet flows within a VoIP (Voice over IP, or Internet Telephony) call. An advantage of the method is that it allows not only end-to-end performance monitoring of flows, but also makes it possible to inspect the transport parameters a specific network or link when delay sensitive traffic transits through it. The results of a preliminary test, to check the validity of the method, are also included.