Abstract: Admission control is one of the key policies to guarantee Quality of Service (QoS) in cellular CDMA networks. In this paper, an optimal Call Admisition Control (CAC) scheme based on Semi-Markov Decision Processes (SMDP) is presented to support multiple class ser-vices for QoS wireless networks. Linear programming formulation is used to find the optimal solution, which maximizes the channel utilization while guaranteeing requirements of QoS con-straints. In addition, weighted fair blocking constraints are used to implement flexible QoS requirements. The numerical results show that the performance of this scheme is better than that of threshold based scheme.