A circuit providing priority telephone service, typically for key personnel; the circuit is activated when the telephone handset is removed from the cradle causing a ringing signal to be sent to the distant unit(s). See verified off-hook .
AUTOMATIC RINGDOWN CIRCUIT
Meaning of AUTOMATIC RINGDOWN CIRCUIT in English
Telecommunication standard terms English vocab. Английский словарь стандартных телекоммуникационных терминов. 2012