Abstract: Disclosed is a means for testing drop wires in digital loop systems which employ optical fiber up to a distant terminal near the subscriber's premises. A test module is provided at the distant terminal to determine the presence or absence of faults on the wires to the customer premises. The results of the test are transmitted via an optical data link to the remote terminal where the results can be accessed by a loop tester at the central office.

Abstract: A subscriber loop carrier system is shown in which coin first and dial tone first pay stations can be serviced through the carrier system without modifying the central office. Coin supervisory states are detected at the central office terminal of the system, translated into unique cyclic codes for transmission through the system and detected at the remote terminal by reapplication of the coin supervisory states at the remote terminal. Coin first and dial tone first modes of operation are accommodated with simple option plugs.

Abstract: A subscriber loop carrier system using digital transmission techniques is disclosed in which remote subscriber loops include two-party lines equipped for automatic number identification. The calling party going off-hook causes an automatic number identification (ANI) test request to be sent to the subscriber location. The ANI response signal is then encoded and transmitted to the central station to indicate which party is initiating the call. The same test for automatic number identification is repeated for any substantial discontinuity in the central office loop current to obtain an updating of the automatic number identification information. Encoded pulse signals are used for both the ANI test request and the ANI response signal.