Transmitting real-time traffic in ad hoc networks is such a complex process that even the packets of a traffic flow interfere among themselves. A large variety of mechanisms to provide Quality of Service guarantees to real time traffic have been proposed in the literature; admission control is one of them. This paper proposes a distributed, stateless, and routing protocol decoupled admission control scheme for ad hoc networks that guarantees average delay to more than one traffic class. During the admission process, probing packets are sent from the incoming node to the receiving node of the flow. Based on the traffic and service envelopes of the probing packets, the receiving node decides whether the new flow is accepted or rejected. The admission control scheme was tested in static networks, where it effectively controls the packet delay. In mobile networks, the algorithm was evaluated varying the amount of mobile nodes, which move with a pedestrian pattern. The operation limits of the admission control were determined, to guarantee maximum delay and to control the packet losses of each traffic class.