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Chapter 13 - Emergency Calls on the Internet

This chapter is devoted to the complex topic of IP-based emergency calls. What makes IPbased emergency calls a complex issue? First of all, an emergency call needs to be routed to the closest Public Safety Answering Point (PSAP). This requires the call to be routed to the PSAP based on the caller’s location, which in turns requires the caller’s location to be determined roughly. | Chapter 13 Emergency Calls on the Internet 13.1 Introduction This chapter is devoted to the complex topic of IP-based emergency calls. What makes IPbased emergency calls a complex issue First of all an emergency call needs to be routed to the closest Public Safety Answering Point PSAP . This requires the call to be routed to the PSAP based on the caller s location which in turns requires the caller s location to be determined roughly. Furthermore it also requires a mechanism to translate the location into the real URI of the PSAP. All of these issues make IP-based emergency calls complex in comparison with regular IP-based calls using SIP. There are three different types of emergency communications of which this chapter covers just the first. Citizen-to-authority communications. This type of communication refers to users dialling an emergency number such as 112 in Europe or 911 in the USA. Usually these are referred to as emergency calls. Authority-to-citizen communications. This typically refers to national emergency centers broadcasting alerting information related to emergency situations. For example in the case of a rough weather condition such as a hurricane or a tsunami an alert can be issued to the population providing instructions for their safety. In some cases this type of emergency communication may require warning messages or instructions to be launched to all citizens or a group of them who are located in a determined geographical area e.g. where a disaster has taken place. Authority-to-authority communications. This refers to the type of communication that takes place between two authorities during an emergency situation. This might be the communication that takes place between a national emergency coordination center and the police fire brigade or hospitals. Typically this type of communication has higher priority than the rest of the calls and it might pre-empt existing calls. When users want to make an emergency call they simply dial the local .