VoIP Emergency Call System And Its Implementation Technology

Among a large number of VoIP service applications,VoIP-based emergency call has become anurgent problem of communication networks.It involves the co-ordination at various levels of theuser terminal, network protocols and provider service.The most important concern is the support ofSIP-based VoIP emergency call.Based on the study and analysis of relevant technological advance and the latest internationalstandards,the dissertation makes an in-depth study on software design and implementationtechnology of SIP-based VoIP emergency call under the ECRIT emergency call system architecture.First of all, The dissertation outlines the background of VoIP emergency call and brieflyintroduces the key technologies of the ECRIT emergency call system architecture and VoIPemergency call.Then, focus is devoted on the SIP-based VoIP emergency call. Based on anoverview of VoIP technology and SIP protocol, the dissertation gives the design and implementationof VoIP emergency call system.It designs the emergency call message structure, message coding and parsing functions andproposes the implementation of the control system of VoIP emergency call system. Detailed designis given of the SIP protocol extended functions, functional modules of the client and the servertogether with the completed C language coding.The dissertation also studies some key technologies for VoIP emergency call systemimplementation, including location information confguration, automatic access to the emergencycall number, call processing at the PSAP, data-only emergency call，emergency call supplementaryinformation, inactivation of call waiting and call forwarding features during emergency call.Finally, the dissertation runs the functional testing on the software of the author developedVoIP emergency call prototype system. The testing results have shown that the system meets the thedesign requirements with reasonable design and correct functions.