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| Number | Title | Issue Date |
| 5566233 | Communication controlling apparatus for a single-line telephone with extensions thereto In a single-line telephone, there are a plurality of extension telephone sets connected by a telephone line and each extension telephone set is connected to a communication controlling apparatus. The communication controlling apparatus includes an alterna... | 10/15/1996 |
| 4771451 | Polarity ring director A polarity ring director for designating a specific party in a multi-party telephone system using polarity encoding to ring only a specific party's telephone includes a solid state bipolar switch connected in series with the subscriber telephone line. The... | 09/13/1988 |
| 4761810 | Programmable selective ringing circuit and method for party telephone line An apparatus and method for decoding ringing signals on a party telephone line coupled to the telephone line and a telephone instrument, according to the polarity of a d.c. voltage level present across the telephone line upon which ringing signals are sup... | 08/02/1988 |
| 4741024 | Selective ringing circuit for a telephone A selective ringing circuit for a telephone line includes a rectifier which is normally connected to the telephone line for rectifying the AC ringing and other signals. The rectified ringing signals will not activate the ringing circuit of the telephone e... | 04/26/1988 |
| 4723271 | Apparatus for selectively alerting party line subscribers An apparatus is described having the capability to selectively alert subscribers in a telephone party line system where different subscriber parties are alerted using different ringing configurations. Subscribers are identified as being a member of a part... | 02/02/1988 |
| 4701949 | Frequency responsive party telephone line selection apparatus and method An apparatus adapted to be coupled into a party telephone line for selecting a ringing signal transmitted on the line from among a plurality of possible coded ringing signals that could be transmitted on the line and for coupling the ringing signal to a t... | 10/20/1987 |
| 4669111 | Polarity ring director A polarity ring director for designating a specific party in a multi-party telephone system using polarity encoding to ring only a specific party's telephone includes a solid state bipolar switch connected in series with the subscriber telephone line. The... | 05/26/1987 |
| 4587380 | Interface for connecting standard telephones to party lines A party line interface for permitting the connection of a standard telephone to a telephone central office which rings selected subscribers by applying a DC ringing potential of a selected polarity to a selected one of the tip and ring lines of the party ... | 05/06/1986 |
| 4435619 | Switching network interfacing telephone-exchange equipment with two-subscriber party line A line loop (a, b) serving two telephone subscribers with sets (U1, U2) each normally connected between ground and a respective line conductor, coupled at the exchange via a line transformer (T) to a voice path, includes a pair of li... | 03/06/1984 |
| 4224476 | Multiparty subscriber loop carrier systems A subscriber loop carrier system is disclosed in which a plurality of telephone subscriber communications channels are frequency-multiplexed on a single wire pair using analog modulation techniques. Supervisory signaling for each channel is accomplished b... | 09/23/1980 |
| 3965307 | Electronic tone ringer An electronic tone ringer for use in telephone subsets. Operating in response to and powered from incoming received ringing signals, the ringer circuitry provides audible multitone signals. The circuitry employed eliminates so-called "bell tapping" or "ch... | 06/22/1976 |
