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Modeling Prepaid Mechanism of VoIP and Messaging Services

Voice over IP (VoIP) allows service providers to offer advanced IP-based services with reduced costs as compared with the traditional telecommunication voice services. This paper proposes a SIP-based prepaid mechanism to handle both the prepaid calls and messaging services in a VoIP system. When both voice and messaging are simultaneously offered, a potential problem is that the delivery of a message during a call may result in force-termination of that call. To address this issue, we describe a strategy to determine if a prepaid message can be sent out during a call session. We propose an analytic model to investigate the performance of this strategy. Based on the performance study, we provide guidelines to select appropriate input parameters for the prepaid mechanism.