| 摘要 |
Apparatus and method for testing a sparing line circuit in a communication system, comprised of a test access concentrator circuit and relay circuitry for connecting the sparing line circuit thereto. The test access concentrator circuit includes a hookswitch polarity detector for detecting the presence of DC battery feed current flowing from the sparing line circuit, and the direction of flow of battery current, and termination circuitry for providing one of either a DC or ANI termination to the sparing line circuit for sinking the DC battery supply current. Signal outputs from the hookswitch polarity detector circuit provide an indication of whether or not the sparing line circuit is present, and if so whether the sparing line circuit has been connected with correct polarity.
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