Data-Only Emergency Calls

RFC 6443 'Framework for Emergency Calling Using Internet Multimedia' describes how devices use the Internet to place emergency calls and how Public Safety Answering Points (PSAPs) handle Internet multimedia emergency calls natively. The exchange of multimedia traffic for emergency services involves a Session Initiation Protocol (SIP) session establishment starting with a SIP INVITE that negotiates various parameters for that session. In some cases, however, the transmission of application data is all that is needed. Examples of such environments include alerts issued by a temperature sensor, burglar alarm, or chemical spill sensor. Often these alerts are conveyed as one-shot data transmissions. These type of interactions are called 'data-only emergency calls'. This document describes a container for the data based on the Common Alerting Protocol (CAP) and its transmission using the SIP MESSAGE transaction.