A Mechanism for Ensuring the Validity and Accuracy of the Billing Services in IP Telephony

The current penetration, but also the huge potential, of Voice over IP (VoIP) telephony services in the market, boosts the competition among telecommunication service providers who promote new services through many different types of offers. However, this transition from the closed Public Switched Telephone Network (PSTN) architecture to the internet based VoIP services, has resulted in the introduction of several threats both intrinsic i.e. VoIP specific, and Internet oriented. In the framework of this paper, we are considering threats that may affect the accuracy and validity of the records of the billing system that the service provider is using for charging the users. We are proposing a simple, practical and effective mechanism for protecting telecommunication service providers and end users from malicious activities originated from the end users and telecommunication service providers respectively. In both cases the malicious activity concerns fraud through the billing system. The proposed mechanism focuses on VoIP services that are based on the Session Initiation Protocol (SIP). However, it can be easily amended to cover other VoIP signaling protocols, as it takes advantage of the underlying AAA network infrastructure to deliver robust time stamping services to SIP network entities.