SIP based VoIP System for E911 Service

Today the world is undergoing a massive shift from the traditional PSTN to All-IP-based Internet telephony, implying an eventual replacement of the PSTN with VoIP sooner or later. Internet telephony users have an expectation to be able to initiate a request for help in case of an emergency. The problem arises for originating calls made to emergency services, where VoIP devices move while identifiers remain the same and the caller's location cannot be provided. So, unfortunately the existing mechanisms to support emergency calls that have evolved within the PSTN, are not appropriate to handle evolving IP-based telephony service. In this paper, we suggest the mechanisms that solve the problem of E911 calling on SIP-based VoIP system using traditional E911 network.