Enhanced 911 Mechanism for Internet Telephony Service

Internet users are rapidly increased, and various services, which use Internet, are invented. Internet telephony service is one of them. As Internet services become an ever more important part of people lives - backed by a marked increase in the number of Internet population - a flow of value-added Web services have been introduced to the market. Internet telephony service was born as a more economical means than public switched telephony network (PSTN) service in terms of call charge, but more recently is being hailed as an efficient means to create new added-values integrating various Internet multimedia services such as video phone, multi-party conference, and instant messaging. After emerging as a star player in the market with innovative technologies, however, VoIP has recently been challenged as the U.S. Federal Communications Commission (FCC) issued an order "requiring all VoIP providers to provide their customers with emergency call service" in May 2005. 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 introduce E911 service and suggest the mechanisms that solve the problem of E911 service calling on SIP-based VoIP system.