A modular electronic circuit board that plugs into a slot on a larger telecommunications chassis, such as a PBX, network switch, or optical multiplexer. Each card provides specific input and output ports, terminating physical lines like copper telephone wires or fiber optic cables. This modular design allows network operators to expand capacity or swap out faulty ports without replacing the entire chassis.
Heard on the job
Go down to the switchroom and swap out the faulty line card in slot four, we just lost 24 analog extensions.