Telephonic communications – Multi-line or key substation system with selective switching... – With intercom system
Patent
1988-09-15
1989-09-19
George, Keith E.
Telephonic communications
Multi-line or key substation system with selective switching...
With intercom system
H04Q 520, H04M 172, H04M 900
Patent
active
048688479
ABSTRACT:
A telephone intercom device is provided for use in a telephone system. The telephone system includes a plurality of telephones interconnected to one another via first and second pairs of conductors, the first pair of conductors also being coupled to an external telephone line. Each of the telephones includes a hook switch associated therewith that is operable to enable the telephone. The intercom device includes a connector for receiving the conductors of the telephone that extend from the hook switch. A pair of telephone call conductors are provided for connecting at one end to the first pair of conductors. A pair of intercom call conductors are also provided for connecting at one end to the second pair of conductors. A mode selection switch is connected at one end to the connector and is operable between first and second positions to connect the conductors extending from the telephone hook switch to one of the telephone call and intercom call conductors. The mode selection switch is biased to the first position and is actuable to the second position upon energization of a relay. A holding circuit is included and associated with the intercom call conductors to maintain the mode selection switch in the second position once the relay has been energized. The holding circuit is disabled when the hook switch is disabled to allow the mode selection switch to revert to the first position. The holding means is also inoperable until the mode selection switch is actuated to the second position. A signalling circuit which is responsive to an electrical signal generates and indication signal onto the intercom call conductors to operate a signaling device in each of the intercom devices. The signalling circuit is isolated from the telephone call connectors and the mode selection switch to allow the indication signal to be generated while the mode selection switch is in the first position to allow an intercom call to be generated without placing an external telephone call on hold.
REFERENCES:
patent: 3665116 (1972-05-01), Holstrom
patent: 4016372 (1977-04-01), Hoehn
patent: 4079212 (1978-03-01), Sasai
patent: 4088846 (1978-05-01), McEowen
patent: 4100375 (1978-07-01), Noller
patent: 4196317 (1980-04-01), Bartelink
patent: 4459434 (1984-07-01), Benning et al.
patent: 4485273 (1984-11-01), Bartelink
patent: 4588861 (1986-05-01), Teich
patent: 4754476 (1988-06-01), Rasmussen et al.
LandOfFree
Telephone intercom device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Telephone intercom device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Telephone intercom device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-374952