Patent ID: 6870903

Claim:
A telecommunications system comprising: a telephone exchange; a customer services terminal having an input connected to said telephone exchange, and having a plurality of outputs individually connected to one of a plurality of telephone lines; a plurality of interface circuits within said customer services terminal, each of said interface circuits being connected to one of said plurality of outputs; self-test means for testing said interface circuits; loop-test means for testing said telephone lines; a self-test relay responsive to said self-test means and operative during a self-test to disconnect said plurality of outputs from said plurality of telephone lines, and to provide self-test conditions to said interface circuits while said interface circuits are disconnected from said plurality of telephone lines; means responsive to said loop-test means, operative to provide loop-test conditions to said interface circuits while said plurality of interface circuits and said plurality of outputs remain connected to said plurality of telephone lines; selecting means for selecting certain of said interface circuits and/or certain of said telephone lines to which said self-test conditions and/or said loop-test conditions are to be applied, while a remainder of said interface circuits and/or a remainder of said telephone lines remain operative with said telephone exchange; a first tip lead and a first ring lead forming each of said plurality of telephone lines; a second tip lead and a second ring lead forming each of said plurality of outputs; a first and second normally-closed self-test relay switch respectively operative to connect said first tip lead to said second tip lead and to connect said first ring lead to said second ring lead when said self-test relay is de-energized during a loop-test; a first and second normally-open self-test relay switch respectively operative to disconnect said first tip lead from said second tip lead and to disconnect said first ring lead from said second ring lead when said self-test relay is energized during a self-test; a loop start relay operative when energized during certain self-tests to connect a termination impedance from said second tip lead to said second ring lead; and a ground start relay operative when energized during other self-tests to connect said second ring lead to a source of ground potential as said second tip lead is maintained in a disconnected condition.