LINE STATUS APPARATUS FOR TELEPHONES

摘要

LINE STATUS APPARATUS FOR TELEPHONES In a telephone installation in which more than one telephone terminal is connected to one pair of conductors - Tip and Ring - a line status apparatus is provided for each telephone terminal, the apparatus sensing a change in line characteristics resulting from an "offhook" condition at any telephone and producing an output which is used to provide an indication. Little or no current is drawn from the telephone lines. Typical examples are sensing variations in AC characteristics, as resulting from voice transmission, ringing tones and the like; sensing DC variations, such as voltage drop when a telephone is "off-hook". Indication is generally visual. - i