Legacy PSAP Gateway to emergency call originations to allow the legacy PSAP to experience call delivery, Automatic Location Identification (ALI) data retrieval, and feature activation the same way as they do today. The Legacy PSAP Gateway must also support an ALI interface over which it can receive and respond to ALI queries from legacy PSAPs. Interfaces to a Location Information Server (LIS) and a Legacy Network Gateway must also be supported by the Legacy PSAP Gateway so that it can perform a de-referencing operation if the SIP signaling from the ESInet includes a location-by-reference. In addition, the Legacy PSAP Gateway must support an interface to an Emergency Call Routing Function (ECRF) in the i3 ESInet to support certain emergency call transfer scenarios. The Legacy PSAP Gateway may also support interfaces to Call Information Databases (CIDBs) to support access to additional non-location data associated with the emergency call, if a reference to such data is provided in incoming SIP signaling. Telcordia GR-3166, Legacy Public Safety Answering Point (PSAP) Gateway Generic Requirements, addresses the external signaling interfaces that must be supported by the Legacy PSAP Gateway, including a SIP interface over which emergency calls will be delivered to it via the i3 ESInet, and traditional MF and/or E-MF interfaces to legacy PSAPs for call delivery. See also 9-1-1 112 (emergency telephone number) Enhanced 911 North American Numbering Plan Next Generation 9-1-1 Public safety department References External links The Development of 9-1-1 and Wireless 9-1-1 Overview, from NENA's website Enhanced 911 PSAP Registry from the Federal Communications Commission website NAED website Telephone services Emergency communication Emergency medicine