A line card or digital line card is a modular electronic circuit on a printed circuit board that interfaces with a telecommunications access network.
A line card typically interfaces the twisted pair cable of a POTS local loop to the public switched telephone network (PSTN). Telephone line cards perform multiple tasks, such as analog-to-digital and digital-to-analog conversion of voice, off-hook detection, ring supervision, line integrity tests, and other BORSCHT functions. In some telephone exchange designs, the line cards generate ringing current and decode DTMF signals. The line card in a subscriber loop carrier is called a subscriber line interface card (SLIC).
A line card can terminate a line supporting voice POTS service, ISDN service, DSL service, or proprietary ones. Some line cards are capable of terminating more than one type of service.
Since an access network element is usually intended to interface many users (typically a few thousand), some exchanges have multiple line terminations per card. Likewise, one network element can have many line cards.
Famous quotes containing the words line and/or card:
“What we are, that only can we see. All that Adam had, all that Caesar could, you have and can do. Adam called his house, heaven and earth; Caesar called his house, Rome; you perhaps call yours, a cobbler’s trade; a hundred acres of ploughed land; or a scholar’s garret. Yet line for line and point for point, your dominion is as great as theirs, though without fine names. Build, therefore, your own world.”
—Ralph Waldo Emerson (1803–1882)
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—Lewis Carroll [Charles Lutwidge Dodgson] (1832–1898)