Abstract: Customer services terminal input connected between telephone exchange and outputs. Interface circuits provide service between input and outputs Test means applies test conditions to interface circuits and/or to outputs associated with the interface circuits, and/or to ring/tip pairs associated with interface circuits, and/or to telephone lines associated with interface circuits Other interface circuits service input to other outputs Test means analog-to-digital converter includes reference input, analog measuring input, ground potential input, and test output Normally de-energized calibration relay has normally-closed switches and normally-open switches. Normally-closed switch connects reference voltage to reference input. Another normally-closed switch connects analog measuring input to test means generated voltage.

Abstract: A telecommunications system includes a telephone exchange and a customer services terminal whose input is connected to the telephone exchange, and whose plural outputs are individually connected to one of a plurality of telephone lines. A plurality of interface circuits within the customer services terminal are individually connected intermediate the input and one of the plural outputs. Self-test means provides for the testing of selected interface circuits. Loop-test means provides for the testing of selected telephone lines. A self-test relay is responsive to the self-test means and operates to disconnect the selected outputs from corresponding telephone lines as self-test conditions are applied to selected interface circuits as these interface circuits are disconnected from the selected telephone lines. The loop test means applies loop-test conditions to selected interface circuits, while the selected interface circuits and the corresponding outputs remain connected to the corresponding telephone lines.

Abstract: Customer services terminal input connected between telephone exchange and outputs. Interface circuits provide service between input and outputs Test means applies test conditions to interface circuits and/or to outputs associated with the interface circuits, and/or to ring/tip pairs associated with interface circuits, and/or to telephone lines associated with interface circuits Other interface circuits service input to other outputs Test means analog-to-digital converter includes reference input, analog measuring input, ground potential input, and test output Normally de-energized calibration relay has normally-closed switches and normally-open switches. Normally-closed switch connects reference voltage to reference input. Another normally-closed switch connects analog measuring input to test means generated voltage.

Abstract: A telecommunications system includes a telephone exchange and a customer services terminal whose input is connected to the telephone exchange, and whose plural outputs are individually connected to one of a plurality of telephone lines. A plurality of interface circuits within the customer services terminal are individually connected intermediate the input and one of the plural outputs. Self-test means provides for the testing of selected interface circuits. Loop-test means provides for the testing of selected telephone lines. A self-test relay is responsive to the self-test means and operates to disconnect the selected outputs from corresponding telephone lines as self-test conditions are applied to selected interface circuits as these interface circuits are disconnected from the selected telephone lines. The loop test means applies loop-test conditions to selected interface circuits, while the selected interface circuits and the corresponding outputs remain connected to the corresponding telephone lines.