| 摘要 |
Monitoring device for telephone sets, which has a preferably fifteen-character digit display device which can be actuated by the dial pulse transmitter of the telephone set and which displays the dialled digits of a telephone number following the order of the dialling operation, which monitoring device is supplied with current from the telephone network, from a battery or power supply unit, is installed in the telephone set, a charge meter or in its own housing, and, in the case of telephone sets with a telephone number memory and an auto-dial mechanism, displays the respective retrieved stored number.
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