Dimensioning radio resources in GSM/GPRS networks is particularly important because of the presence of mixed traffic: voice and data. Appropriate models are required especially when the implemented resources allocation strategy is Partial Partitioning. In this paper we propose three mixed traffic models suitable for dimensioning cells using PP scheme. In order to validate our models we define and compare several performance parameters: blocking probability for voice, throughput (total and per user), cell utilization and blocking probability for data. The models based on combined FR and HR voice traffic technique and the DHR voice technique implement an optimal use of resources based on half-rate mobiles capability and re-packing mechanisms. The mixed models we proposed could be used for dimensioning radio resources in GSM/GPRS networks in order to ensure the adequate QoS level for each type of service according to the voice and data traffic loads.