Abstract Call admission control is typically devised so as to employ the declared worst-case traffic descriptors for incoming calls, a solution resulting in poor bandwidth utilization. A measurement-based admission scheme is an appealing alternative, offering adaptivity to the changing traffic conditions, while allowing statistical multiplexing gains to be exploited. In this paper, we examine the problem of determining which traffic characterization a measurement-based admission control algorithm should require of sources requesting access. We also propose an adaptive measurement-based admission control algorithm that simplifies the estimation process. We test the new algorithm under different traffic scenarios and show that a high utilization level is achieved without violating delay-based QoS guarantees.