Power line carrier multi telephone extension system for full duplex conferencing between telephones
Patent 4475193 Issued on October 2, 1984. Estimated Expiration Date: 
September 30, 2002. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
September 30, 2002. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3864521 Telephone extension system utilizing power line carrier signals Remote signalling to a telephone line utilizing power line carrier signals Carrier current communications system Patent #: 4239940 InventorAssigneeApplicationNo. 06/431400 filed on 09/30/1982US Classes:370/295, Frequency division340/310.11, REMOTE CONTROL OVER POWER LINE370/260, Conferencing379/202.01, Conferencing455/402Over power lineExaminersPrimary: Olms, Douglas W.Assistant: Scutch, III, Frank M. Attorney, Agent or FirmInternational ClassesH04B 3/54 (20060101)H04M 1/72 (20060101) AbstractIn a power line carrier telephone extension system for transmitting electrical signals between the telephone line and an extension telephone over the AC electric power line available at a telephone subscriber's premises, that includes a main station for processing signals between the subscriber's telephone line and power lines and an extension telephone of the system that plugs into the power line, means that provides for a plurality of such extension telephones all of which can place calls to the telephone line, answer calls from the telephone line and conference together in full duplex communication. | |
