Routing mechanism for VoIP emergency calls in IP Multimedia System

The emergency call service is to forward the emergency call originated from subscribers in an emergency situation to the nearest PSAP (Public Safety Answering Point) based on their location. However, it is relatively difficult to measure an accurate location of subscribers of the internet telephone based on the IP address. Therefore, the paper introduces methods and implemented examples in the KT for routing an emergency call as well as it proposes the structure of routing tables based on the location information of the subscribers in IMS (IP Multimedia System).