scope:

This standard provides analog interface requirements for the connection of a Customer Installation (CI), such as Private Branch Exchanges, to an Enhanced 911 system. The analog interface allows the CI to transmit the caller's emergency service identification (CESID) information to an Enhanced 911 system in applications in which multiple terminals share Enhanced 911 switched access. The requirements of this standard apply at the Network Interface (NI). The NI is the point of interconnection between the telecommunication carrier network (the Network) and the customer premises wiring and equipment (the CI). The requirements cover the electrical characteristics of the Network and the CI and the interactions necessary for a CI to complete a call through an Enhanced 911 system. The voicegrade transmission performance of the network or the CI is not covered.

The reverse-battery signaling interface described in this standard is for outgoing calls only and employs a network-provided battery source. It is significantly different than the interface described in T1.405-2002, which describes an interface that uses loop reverse-battery signaling with a CI-provided battery source.¹

NOTE - Although some existing analog interfaces use other signaling methods, such as E&M signaling, the objective of this standard is the use of network-provided reverse-battery signaling.

Multiple carriers may be involved in providing the transmission and signaling paths between the CI and the Enhanced 911 system. The interface between the carrier and the Enhanced 911 system or intermediate carrier-to-carrier interfaces are not covered in this standard.

The signals that the network presents at the NI are basically of two types: normal telecommunications system voltages and currents, and voltages and currents due to maintenance activities. These are specified in this standard.Abnormal voltages and currents that are the result of the environment (e.g., induced voltages and currents or lightning) are not covered in this standard.

Tariffs, contracts, or regulatory acts in various jurisdictions may contain additional or more stringent requirements than those in this standard.

Purpose

This standard provides network-to-CI interface requirements for analog voicegrade Enhanced 911 switched access using reverse-battery signaling with a network-provided battery source. These requirements are intended to assist carriers, end-users, and manufacturers.

¹ When Enhanced 911 switched access is implemented via a DS1 interface using robbed-bit signaling, the signaling states are the same as those transmitted by an interface historically known as Dial Pulse Originating (DPO) that is described in T1.403.02-1999.