Untrue.there is no blue/white.
For the standard 4 pair cable found in most homes, blue and white/blue is close enough.
When you get into real phone wiring with cables of more than 5 pairs, there's a group/pair color system.
The ring wire will have the pair color (blue,orange,green,brown,slate) as the major color and the group color (white,red,black,yellow,violet) as the minor color, i.e. mostly blue with a white trace. On the corresponding tip wire, the group color will be the major color and the pair color will be the minor color, i.e mostly white with a blue trace. blue/white + white/blue are pair 1 of group 1, blue/red + red/blue are pair 1 of group 2.
I'm currently holding a piece of cat5e manufacturer/ Superior EssexAll the CAT5 I have run has always had a blue with a white trace and a white with a blue trace. This continued for the other pairs ie O/w and W/o etc.
feel free to post a manucfacturer. While I happened to reach over to the shelf and grab a piece of the cable I did, it isn't the only cable I have ever worked with.Nap, most wire mfg. use blue with white, and white with blue. You have found the oddity.
Well now you've seen it and your life is complete.while I admit I could be wrong, I stick by my statement that I have never seen a cable with a blue/white-white/blue pair.
even though it doesn't fulfill the challenge, I'll give it to ya.Comtran Cat3. Its on the Home Depot web site. Pretty obvious there's white (group color) traces on the ring wires. No idea if it would actually come like this. Don't think its common any more (since its cheaper to not add the white), but it was typical many years ago. I kind of remember making up patch cables back in the 80's and those cables had blue/white. Of course that was the 80's and that's a decade best left forgotten.
Well now you've seen it and your life is complete.
Do you have some cat5 cat5e, cat6 or cat6a with a blue with a group color trace in it? It might be out there somewhere but I've yet to see it.