Call admission control mechanisms play an important role in heterogeneous wireless networks where different radio access technologies will coexist to grant Quality of Service (QoS) in a network. They are used to decide whether or not an incoming service request will be accepted according to an admission constraint as well as determining in which radio access technology among the available it will be connected. In this paper, we propose an adaptive bandwidth management and call admission control scheme for heterogeneous wireless networks. The proposed scheme takes into account the separation between the incoming traffic for each class and prioritizes handoff calls over the new calls. The objectives of the proposed adaptive CAC approach are to guarantee QoS requirements of all accepted calls, reduce new call blocking probability and handoff call dropping probability and maintain efficient resource utilization.