| 摘要 |
A hold and dial monitor accessory is provided for use with a conventional telephone instrument connected across a subscriber service pair extending from a central office. The hold and dial monitor accessory is bridge connected across the telephone service pair and includes a manually actuable and releasable line seize switching circuit for controlling a line hold circuit connectable across a communications loop through the central office. The line seize switching circuit has an internally established time constant for automatic line release whenever a telephone handset is taken off-hook, and an audio amplifier and loudspeaking circuit is provided for amplifying audio information present on the telephone service pair during the interval when the line hold circuit is holding the communications loop.
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