sold as the Meridian Norstar in some markets, until the mid-1990s A large-scale switch based on the DMS-100 is sold as the Meridian SL-100 Resellers, and accessory manufacturers frequently but erroneously use the phrase "Meridian Option" to refer to the Meridian 1 range, to distinguish it from the smaller and larger Norstar and SL-100 Digital Line Card A digital line card is an intelligent peripheral equipment (IPE) device which can be installed in the IPE module. It provides 16 voice and 16 data communication links between a Meridian 1 switch and modular digital telephones. The digital line card supports voice only or simultaneous voice and data service over a single twisted pair of standard telephone wiring. When a Meridian digital telephone is equipped with the data option, an asynchronous ASCII terminal, or a PC acting as an asynchronous ASCII terminal, can be connected to the system through the digital telephone. Physical description Digital line cards are housed in the Intelligent Peripheral Equipment (IPE) Modules. Up to 16 cards are supported. The digital line card circuitry is mounted on a by ( by ) double-sided printed circuit board. The card connects to the backplane through a 160-pin edge connector. The faceplate of the digital line card is equipped with a red LED that lights when the card is disabled. When the card is installed, the LED remains lit for two to five seconds as a self-test runs. If the self-test completes successfully, the LED flashes three times and remains lit until the card is configured and enabled in software, then the LED goes out. If the LED continually flashes or remains weakly lit, there is a fault detected in the card. Functional description The digital line card is equipped with 16 identical digital line interfaces. Each interface provides a multiplexed voice, data, and signaling path to and from a digital terminal (telephone) over a 2-wire full duplex 512 kHz Time-division_multiplexing digital link. Each digital telephone and associated data terminal is assigned a separate Terminal Number (TN) in the system database, giving a total of 32 addressable units per card. References Extracts from Nortel IP Telephony TCM Loop Time Compression Multiplexing (TCM) is the standard communication protocol used by Nortel digital telephones on a 2-wire tip and ring circuit. Each digital phone line terminates at a station port on a Digital Voice Card (DVC) in the PBX. The circuit interface operates by