ABSTRACT: This document identifies the proposed generic requirements for Half-Ringer (HR) units that, in the view of Telcordia, shall be met in order to meet the typical needs of a LEC environment. The HRs covered by this document are intended for voice frequency loops only and may not work on digital loops, Integrated Services Digital network (ISDN), or XDSL services, such as Asymmetric Digital Subscriber Line (ADSL). An HR is intended to be installed in parallel with the phone line at the customer's premises. An HR provides a minimum circuit impedance of 0.5 Ringer Equivalence Number (REN). One REN is considered the average circuit impedance for an electromechanical telephone set. Electronic telephone sets may have RENs below 0.5. The HR normally consists of a resistor Zenor diode, diode, and a capacitor. HRs are intended for use with Mechanized Loop Testing (MLT), and not Automatic Line Insulation Testing (ALIT). MLT sends out a signal looking for the HR.

This testing method does not sectionalize like a Maintenance Termination Unit (MTU), so there is no isolation indication between the network and the customer.