This ATIS Standard defines the Request For Assistance Interface (RFAI) between the Emergency Services Next Generation Network (ES-NGN) and a Public Safety Answering Point (PSAP). Initially, Requests for Assistance are emergency voice calls and RFAI defines the foundation for supporting future types of Requests for Assistance. The RFAI specification may be used by PSAP CPE vendors and Network Equipment Providers that are implementing IP-based solutions as part of the transition and evolution to the Next Generation 9-1-1 emergency services (NG9-1-1).