ATTACHMENT TO TELEPHONE SET TO TEST ITS CONDITION Russian patent published in 2000 - IPC

FIELD: telephone communication, facilities protecting equipment against users' negligence. SUBSTANCE: proposed invention makes it possible to receive call signals when telephone receiver is off the telephone set as it displays additional functional capabilities as compared with other known aids for protection and test of telephone sets which is technical objective of invention. This objective is achieved thanks to usage of microprocessor which carries out in accordance with program test of duration of transmission of signal " busy in subscriber's line and forming after specified time interval signal ensuring disconnection of speech part of telephone set and power supply of microprocessor via contacts of second optoelectronic relay across its output. EFFECT: employment of additional functional capabilities for protection against users' negligence. 9 cl, 1 dwg