To anyone interested in historical information, the current 568B standard was originally referred to as "AT&T 258A". It was kind of stupid because that was simply referring to the ever-popular adapter made by Western Electric/AT&T/Lucent/Avaya/Whatever to convert an existing 1A2 (25 pair) station cable to six four-pair modular jacks.
A four-pair modular jack IS NOT an RJ45, but that's another issue entirely. I will bore you with that subject later.
Anyway, early electronic telephone sets made by Western Electric for AT&T and the Bell companies used their special 4-pair jack. They intentionally configured the pinouts differently since it was way too easy to plug a 2-pair plug into a 4-pair jack. Their electronic phones (Dimension METS, Horizon METS, etc.) required separate pairs for power and data, they arranged the jack so that pairs would be in "protected" positions. This would avoid accidental contact through a 2-pair cord insertion and the potential for a blown fuse. Hence, the AT&T 258A standard was born. They seemed to have developed this standard to protect themselves from avoidable service calls.
I am pretty sure, but not positive that data rode on pins 1/2 (W-Or) and power was on pins 7/8 (W-Bn). If I am correct, this left pins 3,4,5 & 6 out of harm's way for the accidental connection of consumer level phones, especially Trimline phones with dial light bulbs connected to pins 3 and 6 (AKA black and yellow). We old timers may also remember "A leads" present on pins 3/6. I really think that they left these pins vacant in their standard to avoid short circuits from A leads, but who really knows?
AT&T developed this standard LONG before EIA/TIA standards "adored" today even wore diapers. This standard might not be "USOC" compatible from an end-user standpoint, but seriously, are any of us on this site concerned about orange or green? I mean, 568A or B is kind of insignificant as long as the jack/patch panel is wired using the same standard.
Where my company is located, there's a huge Bell/Avaya presence because of the huge Federal Government market, so AT&T's 1974 era wiring standard is the norm. Makes perfect sense to me!
