E9-1-1 Network to PSAP Access Interconnection Specifications - Session Initiation Protocol (SIP)
Document Number GR-3114
Issue Number 01
Issue Date Oct 2003
ABSTRACT: Telecommunication networks have traditionally focused on the support of voice traffic and voice services, resulting in a Public
Switched Telephone Network (PSTN) that is optimized for voice traffic and services, and that has high quality and reliability. The high
growth of data services and the explosive growth of the Internet, with its accessibility to both business and residences, has forced a
new way of looking at the voice and data infrastructure, popularized the deployment of packet switching, and spawned Next Generation
Network (NGN) concepts. Both new and some traditional network service providers are making use of these concepts to provide voice and
data service offerings to traditional PSTN customers.
Conventional services provided to the emergency services sector build on PSTN switching features and capabilities, but have
additional functional and special requirements that are supported in conventional networks by specially equipped switching systems
known as E9-1-1 tandems. Emergency calls originated in the PSTN are directed to an E9-1-1 tandem that selectively routes the call to an
appropriate Public Safety Answering Point (PSAP) based on routing data maintained in E9-1-1 Databases. This functionality is described
in other generic requirements documents including GR-2956 and GR-3017. The conventional interfaces between the serving E9-1-1
tandem and the PSAP are typically Multi-Frequency (MF) signaling based access trunks, with some custom Integrated Services Digital
Network (ISDN) interface implementations. The features, capabilities, and signaling supported by the MF-based trunk interface are
described in GR-2953. Companion documents GR-2967 and GR-2968, describe requirements for National ISDN network access
interfaces to the PSAP, but are not widely implemented.
There are several competing and complementary protocol approaches to support VoIP in various forums: Session Initiation Protocol
(SIP) which is being defined by the Internet Engineering Task Force (IETF); H.323, defined by the International Telecommunication Union
- Telecommunication Standardization Sector (ITU-T), and H.248/Gateway Control Protocol, a cooperative effort of ITU-T and IETF. This
document describes access interconnection architectures and interfaces between conventional E9-1-1 tandems and PSAPs that use a
SIP-based network access architecture.
This document provides proposed generic requirements for the signaling between an E9-1-1 Service Provider's network and an E9-1-1
PSAP that makes use of a packetized voice architecture and Internet protocols for network access interconnection. In particular, this
document describes the use of SIP signaling to support conventional E9-1-1 tandem functionality.
This document specifies the interface architecture, interface protocol, messages, signals, conditions, and events that occur for
exchange of information between the E9-1-1 Service Provider's Network and the PSAP CPE to invoke, control, and deliver the functions
and features that are supported by an E9-1-1 tandem. The signaling for this interface may be applied in various packet-switched
architectures, for the interface between various elements. The physical interconnection, the capabilities affecting the interface,
the performance objectives/requirements, and the interface provisioning, are also described.
This GR also includes one or more Issue List Reports (ILRs) that details open or closed technical issues in the main document. The
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