An improved Range Extender with Gain (REG) comprises a floating loop current detector, a new dial pulse reshaper and a new control logic circuit. The loop current detector is powered by means of a floating power supply which renders the detector insensitive to spurious common-mode subscriber loop currents. The dial pulse reshaper comprises logic gates with two feedback paths for regenerating minimum make and break periods. The control logic circuit for controlling the relays in the REG is an asynchronous logic circuit particularly designed to avoid conventional differentiation circuits and timing problems associated with Automatic Number Identification.

To generate a ringing signal by means of a subscriber line interface circuit having two final stages, each for supplying an individual subscriber line wire, one of the subscriber line wires is connected to one of the input terminals of an operational amplifier, the other input terminal of which being connected to the interconnecting point between two series connected resistors having the same resistance. The output terminal of the operational amplifier is connected, via a first resistor, to a current input terminal of the subscriber line interface circuit for generating a first current. A signal generator, via a second resistor, is also connected to said current input terminal for generating a second current. The final stages of the subscriber line interface circuit are supplied with current from current input terminal to drive the final stages to generate the ringing signal.

The local battery and elements of a booster circuit of the energy storage-energy discharge type of swinging choke power converter are connected in series in the subscriber's local battery loop of a carrier subscriber station terminal. A smoothing capacitor is connected across the battery and booster circuit elements for providing a loop voltage there that may be greater than a local battery voltage where a subscriber Touch-Tone telephone set is off-hook and sending calling signals. Current in the circuit elements is monitored for controlling the duration of the portion of a cycle of operation of the converter during which energy is stored by the choke and, thus, maximum current drain from the battery. In an alternate embodiment, the smoothing capacitor is connected across only circuit elements.

A parallel-T filter network is used in a telephone ring trip circuit to provide one path for A.C. ringing signals to the exclusion of D.C. current and a second path for passing D.C. current through the ring trip relay to the exclusion of A.C. ringing signals having a predetermined frequency.

An improved long line adapter circuit designed to provide ringing supervision, pulse repetition and adequate transmission current for abnormally long subscriber loops and which may be used either at a central office or at a midplacement point to couple a subscriber facility to the central office, is disclosed. Included in the long line adapter circuit is a subscriber circuit and a central office circuit. A line coupling transformer is employed to provide audio coupling between the central office and subscriber circuits. A solid-state pulsing circuit is included in the subscriber circuit to respond to dialing at a subscriber subset and to a receiver thereof being placed in an off-hook condition. The adapter circuit is designed to be used with external power supplies providing either the standard 48 volts for normally distant subscriber loops or to provide a total of 96 volts for very long subscriber loops. A voltage converter or booster circuit and an off-hook sensing circuit may be included in the adapter circuit for the purpose of internally developing the additional + 48 volts for very long subscriber loops while employing the normal negative 48 volt external power supply.