With 25 pair connectors (Amphenol, Amp, Cinch, etc.), pins 26 and 1 are always white/blue and blue/white, respectively. For cables that connect to stations or trunks, this doesn't normally come up for discussion. The difference is when cables using these, or similar, connectors might have a brand-specific pin configuration. This is often the case with cables that connect between cabinets.

The question of 'flipping' or reversed polarity really applies more to modular cords. Standard line cords for telephone sets are usually flipped. The polarity correction, if necessary, it made by the jack inside of the telephone set itself. Of course, the flipping of pairs in modular cords used for T1/PRI or Ethernet are a more common issue. In those instances, there is no in-between. It has to be maintained straight-through polarity in most instances. The exceptions are fairly rare though.

Ed Vaughn, MBSWWYPBX