A line card is:
1) A printed brochure that lists the names, descriptions and manufacturers of products sold by a third party, like a distributor, sales representative or value-added reseller (VAR). These 'product line cards' can be used in sales calls or offered for download to be used by potential customers as useful reference for comparison of product specifications and costs.
2) An electronic circuit on a circuit board that interfaces between subscribers to a telecommunications network and the rest of the network. A line card have commonly been used to interface the twisted pair cable of a POTS local loop with the public switched telephone network (PSTN). Line cards used on the PSTN may have many functions, including:
- conversion of voice transmissions from analog to digital or vice versa
- detection of off-the-hook receivers
- other BORSCHT functions, depending on the circuitry on the card
BORSCHT stands for Battery feed, Overvoltage protection, Ringing, Supervision, Codec, Hybrid and Testing.
BORSCHT functions traditionally used in POTS telephony, including signaling, line supervision and telephone terminal operation, are increasingly integrated into a chipset by semiconductor companies. These chipsets allow for low-cost implementation of a standard POTS telephone interface for connecting to non-traditional telephony networks like cable television , fiber optic , VoIP and WiFi.