Extending SIP to handle communications in emergency situations

Current technological achievements enable users to be reachable through a number of telecommunication devices, network operators, as well as services and applications. This capability can be very important especially in emergency scenarios where some of the access networks or applications may fail. However, existing protocols and mechanisms lack a transparent and dynamic solution to achieve this feature. To tackle this issue, we suggest minor extensions in the SIP protocol as well as the use of middleware to allow calling users to dynamically select the best way to route their requests towards called users. These extensions are described in detail while execution examples are also provided.