Third generation mobile networks is expected to provide services to users, while guaranteeing acceptable QoS (Quality of Service).UMTS is a typical example of these new networks. Thus, this paper is focused on UMTS multimedia domain and its strategies of control of session and resources pre- reservation. In order to offer the various services, while respecting acceptable required level of QoS, it is necessary to guarantee minimum QCSE for each service. Resources managers which we designed are then oriented towards the use of pre-reservation with policies to manage consensus. This orientation is also considered by 3GPP which adopted COPS and SIP protocols for the procedures of session authorization and domain resources IM of UMTS network. In such context, the work developed in this paper is focused towards the setting up of a consensus protocol included inside management and check procedures for resource reservation for multimedia services in UMTS/IP network. The evaluation of the feasibility and of the consensus constitutes the main contribution of this work.