Abstract. We propose a micro-payment scheme for symmetric multihop cellular networks that encourages intermediaries to transmit packets and recipients to provide auditing information. Our scheme is an extension of [6], where the authors addressed the simpler asymmetric case. We then analyze the possible rational abuses to our protocol, and construct a detailed statistical model to detect attacks. We show that for typical applications, the statistical detection model we develop will detect cheating very rapidly. For example, in a VoIP application, one particular attack will be detected within a dozen of seconds.