PURPOSE: To provide a call priority function, by monitoring the usage state of a telephone line corresponding to a call request signal transmitted from a terminal device, and connecting the telephone line to the terminal device when the line is not busy.
CONSTITUTION: When the call request signal from terminal devices 3, 4 is incoming, only when the line 1 is dicriminated that it is in the idle state based on an output signal of a line monitor circuit 107, a network controller 100 closes the DC loop of a subscriber telephone line 1 under the disconnection state of the line 1 with switching circuits 101, 102 with a telephone set 2. Further, a call reception signal is transmitted to the terminal device 3, 4 and a selection signal is transmitted to an exchange based on the selection information given from the terminal devices.
OGAWA FUKUE
TSURUTA YUUZOU
KANAI KAZUO
OKADA KUNIAKI
MORITA YUUICHI
SHIRAI KAZUHIKO
MATSUBARA TATSUO
KONNAI SUEO
NIPPON TELEGRAPH & TELEPHONE
NIPPON ELECTRIC CO
| JPS5555655A | 1980-04-23 | |||
| JPS55140994A | 1980-11-04 |