scope:

This standard provides network-to-customer installation (CI) interface requirements for Direct Inward Dialing (DID) analog voicegrade switched access using loop reverse-battery signaling. DID is a feature of PBX and Centrex systems that permits direct access to a terminal served by a PBX or Centrex system from a carrier network without assistance from the PBX or Centrex attendant. The interface described in this standard uses loop reverse-battery signaling in connection with a one-way trunk that is outgoing from the network and incoming to the CI (see Figure 1.)

The loop reverse-battery signaling interface described in this standard employs a customer-installationprovided battery source. It is different from the interface described in T1.411-2001, Interface between carriers and customer installations - Analog voicegrade enhanced 911 switched access using networkprovided reverse-battery signaling, which describes an interface that uses reverse-battery signaling with a network-provided battery source.

Multiple carriers may be involved in providing the network transmission and signaling paths to the CI. Intermediate carrier-to-carrier interfaces are not covered in this standard. Also, this standard does not cover the voicegrade transmission performance of the network or the CI.

The network applies two types of signals to the Network Interface (NI):

- Normal telecommunication 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 hits) 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

The purpose of this standard is to provide network-to-CI interface requirements for DID analog voicegrade switched access using loop reverse-battery signaling with a customer-installation-provided battery source. The requirements and recommendations are intended to assist carriers, manufacturers,and users of products to be used in or connected to the switched network to understand the characteristics of existing networks.

Application

The interface described in this standard provides a means for the network to transmit address information to the CI. The address information permits the CI to route the call to a specific terminal1 when multiple terminals share switched access. To utilize the interface described in this standard, the CI must have telephone numbers assigned to each terminal that can be reached from the public network.

In this standard, the public switched network is referred to as the Network and the customer premises wiring and equipment as the Customer Installation (CI). The interface between the carrier network and the CI is known as the Network Interface (NI). The NI is the same as the demarcation point defined in Part 68 of the FCC Rules and Regulations (see Annex F). This standard assumes that the CI terminal equipment meets the technical requirements of TIA/EIA-IS-968, which contains technical criteria to protect the network from harm. The standard also assumes that the customer premises wiring meets the technical requirements in Part 68 of the FCC Rules.

Because of the wide range of switching equipment, access lines, and CIs used in North America, conformance with this standard does not guarantee interface compatibility under all possible operating conditions. The NIs described in this standard may not be universally available.

In accordance with ANSI guidelines, two categories of specifications are used, mandatory requirements and recommendations. Mandatory requirements are designated by the word shall and recommendations by the word should. The mandatory criteria generally apply to signaling and compatibility and specify the acceptable levels in these areas.