There is a great demand on multimedia applications with Quality of Service (QoS) in wireless/mobile networks. In this paper, we propose an optimal call admission control framework with bandwidth reallocation algorithm (CAC- BRA) for adaptive multimedia services in wireless/mobile networks, where the bandwidth of an ongoing call is time- varying during its lifetime. The optimization is in the sense of optimizing the revenue and satisfying QoS requirements. We adopt semi-Markov Decision Process (SMDP) approach to model call admission control and bandwidth reallocation algorithm at the same time. The proposed approach allows us to make decision on call admission control, as well as bandwidth reallocation. Simplex method in linear programming is used to solve the optimal decision problem. Numerical results reveal that the proposed CAC-BRA scheme adapts itself well to time-varying multimedia traffic, achieves optimal revenue, and satisfies QoS to upper bound handoff blocking probability.