ABSTRACT: Issue 2 of GR-3165, Emergency Services Border Control function (BCF) Generic Requirements, replaces Issue 1.

The National Emergency Number Association (NENA) long term solution for emergency calling, referred to as the i3 Solution, assumes end-to-end Internet Protocol (IP) signaling from the Voice over IP (VoIP) endpoint to an IP-enabled Public Safety Answering Point (PSAP), with callback and caller location information provided to the PSAP with the call. The i3 Solution introduces the concept of the Emergency Services IP Network (ESInet), which is an IP-based inter-network (i.e., network of networks) shared by all agencies that may be involved in providing assistance during an emergency. A local ESInet, which would typically be county-wide, will be interconnected to a neighboring county's ESInet for mutual aid purposes. Because ESInets are IP-based, such interconnections will allow any agency to communicate with any other agency or service on one of the interconnected ESInets.

The National Emergency Number Association (NENA) views an end-to-end architecture consisting of originating networks and Emergency Services IP Networks (ESInet). PSAPs, which use as well as provide services on the ESInet, will also support internal networks. The Border Control Function (BCF) is an important functional element of the i3 Solution architecture because it provides the first line of defense against deliberate attacks on the ESInet. It is expected that PSAPs will also support a BCF between their internal networks and the ESInet. The BCF provides secure entry into the ESInet for emergency calls presented to the ESInet by incorporating firewall and admission control functions, as well as anchoring of session and media, and other security mechanisms to prevent deliberate or malicious attacks on PSAPs or other entities connected to the ESInet. The BCF is in the path of all call signaling and media. As a result, this element must be highly reliable.

This new element is critical to allow secure entry into the ESInet for emergency calls presented to the ESInet. This component also provides functions to ensure the smooth processing of emergency calls/sessions, including signaling protocol, repair, translation, and interworking, codec negotiation, support for Qos/priority markings, and support for emergency call transfer.

This document is the only public document that fully describes the functionality, interfaces, and operations requirements associated with an emergency service Border Control Function.

Issue 2 includes:

• Updates to the i3 functional Architecture diagram to align with the latest draft on NENA 08-002, NENA Function and Interface Standards for Next Generation 9-1-1 Version 1.0 (i3)
• Modifications to align the terminology used in this GR with the terminology used in the draft NENA i3 Stage 3 specification, NENA 08-003, Detailed functional and Interface Specification for the NENA i3 Solution - Stage 3
• Updates to clarify the functional definition of the Border Control Function
• Inclusion of an automated interface that the BCF provides to downstream systems to assist in identifying sources of calls associated with attacks on the system
• Modifications to requirements dealing with Back-to-Back User agent (B2BUA) functionality within the BCF in support of emergency call transfer.