ABSTRACT: This document provides generic requirements for a Legacy PSAP Gateway to support the delivery of 9-1-1 calls that are routed via Emergency Services IP Networks (ESInets) to legacy PSAPs. The Legacy PSAP Gateway is expected to provide interworking and other functionality necessary for calls routed via i3 ESInets to be delivered to the appropriate legacy PSAP.

This document defines the required functions, interfaces, and data that must be supported by the Legacy PSAP Gateway to accept and process emergency call requests routed via the i3 ESInet, to use the information received in incoming signaling to support call and Automatic Location Identification (ALI) data delivery, to process ALI and feature invocation requests initiated by a legacy PSAP, and to interwork the incoming Session Initiation Protocol (SIP) signaling with traditional Multi-Frequency (MF) or Enhanced MF (E-MF) signaling as appropriate for the legacy PSAP to which the emergency call is to be delivered.

This element is critical to allow continued support for emergency call delivery to legacy PSAPs as the Emergency Service Network and PSAPs evolve to an IP-based architecture. Without this component, there will be no way to deliver emergency calls that are routed via ESInets to legacy PSAPs. Delivery of emergency call originations via an ESInet to legacy PSAPs will require some type of gateway system in the call path to interwork the call signaling and support existing PSAP feature functionality.

This document is the only public document that fully describes the functionality, interfaces, and operations requirements associated with a Legacy PSAP Gateway.

This GR is being reissued to reflect changes to the definition of the Legacy PSAP Gateway as defined in draft NENA 08-003, Detailed Functional and Interface Specification for the NENA i3 Solution - Stage 3, Version 2. Specifically, Issue 3 of GR-3166-CORE includes the following changes:

• Updates to reflect support for receipt of Additional Data Associated with a Call, Additional Data Associated with a Location, and Additional Data Associated with a Caller, and for delivery of Emergency Incident Data Document (EIDD) data structures on transferred emergency calls.
• Updates to address support for the delivery of Teletypewriter (TTY) calls.
• Clarification of default/alternate routing scenarios.
• Clarification regarding the use of the MSAG Conversion Service (MCS).
• Updates to align Session Initiation Protocol (SIP) signaling details with NENA 08-003v2.
• Updates to clarify timing requirements applicable to the Legacy PSAP Gateway.
• Updates to align logging requirements with current draft of NENA 08-003v2.
• Figure depicting Legacy PSAP-to-i3 ESInet Interconnection Architecture updated to align with draft NENA 08-003v2.