Abstract Quality of service (QoS) for voice over IP network is not consistent because of absence of dedicated links as in circuit switched (CS) network. Because of wider mobility to users in UMTS network and voice over IP network being low cost service, performance evaluation for VoIP service over UMTS network is realized more important. Prioritized forwarding strategy to different traffics can be controlled allocating Forward Access Channel (FACH) Scheduling weights in Radio Network Controller (RNC) and Resource Reservation Protocol (RSVP) for the resource allocation like buffer space, bandwidth etc. In this paper, End-to-End QoS of UMTS is mapped to external IP network with Differentiated Service Code Point (DSCP) field in IP packet header specifying different per hop behavior (PHB) and significant improvement in QoS of VoIP service over UMTS network has been observed. Hybrid model of QoS enhancement with DiffServ Code Point integrated to FACH scheduling weight inside UMTS network and RSVP scenario has been studied in this work and the model has been purposed to reduce End-to-End delay maintaining better Mean Opinion Score (MOS).