End-to-end call setup delay is one of the most important grade of service (GoS) parameters for VoIP networks with Session
Initiation Protocol (SIP). A typical subscriber wants to have a connection established as soon as possible. From the operatorís perspective
call setup time is also crucial because he needs to know how probability of successful packet transmission on SIP links is related to a call
setup delay. Then he can make calculations how many resources are needed to guarantee such a transmission. In this paper we proposed the
model for end-to-end call setup time calculation. The fundamentals of the model are to check all or almost all (highly probable) possible
situations during the call setup. Formulas for calculation are included and results of numerical calculation are presented. Comparison against
the values obtained from the simulation shows that it is possible to make calculations of end-to-end call setup time and prepare the discrete
cumulative distribution function for a trapezoid model in reasonable time using the proposed model.