1000BASE-T is a standard for Gigabit Ethernet. While 100BASE-T Ethernet only uses 2 pairs of the cat5 cable, 1000BASE-T uses cat 5e or cat 6 cable, and utilizes all 4 wire pairs and a different modulation technique. The standard was approved by the IEEE in 1999.

100BASE-T uses one twisted wire pair for transmit and one for receive exclusively in a three level MLT-3 Encoding scheme.

1000BASE-T uses all 4 pairs for bidirectional send and receive in a 5-level pulse amplitude modulation (PAM-5) technique.