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Category 4 is a description of a cable that consists of four unshielded twisted-pair (UTP) copper wires with a data rate of 16 Mbit/s and performance of up to 20 MHz. It was used in token ring networks, 10BASE-T, 100BASE-T4, and is no longer common or used in new installations. It is used in telephone networks which can transmit voice and data from 12 Mbit/s to 16 Mbit/s. It was quickly superseded by Category 5/5e cable, both of which have 100±15 ohm impedance.
Category 4 is not recognized by the current version of the TIA/EIA-568 data cabling standards.
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