Twisted Pair Demonstrates Enhanced PTT Functionality for Mobile Workers Using Smartphones, Tablets and Other Handheld Computers over Any Network ...

I have come across several times, though, a cable that only has 2 twisted pair of cables with only 4 of the pins being used and the remaining pins of the RJ45 connector left open.

But Ethernet didn’t start with twisted pair cable. [Mark] and [Ben] at The Serial Port YouTube channel are taking a deep dive into the twisted history of Ethernet on twisted pair wiring.