A description of queuing delay mechanisms for VoIP traffic is a complex ask. This paper deals with a
mathematical computational model that is able to predict a estimated delay of packets in RTP flows, especially dealy
variation in routers handling RTP packets in priority queue. We applied M/D/1 queuing model and we expressed a
probability of RTP packet waiting in the queue. We describe all partial VoIP delay components and mechanisms, its
generation, facilities and mathematical formulations. We present new approach to the delay variation model and we
have confirmed its validity by an experiment.Scopu