See also: crossover T1 cable

Two devices with PRI interfaces can be connected together with a PRI crossover or null-modem cable.

• Cisco doc
• Gcom doc
• Adtran doc
• Sangoma Doc

It should be emphasized that while a common ethernet patch cord can by used just fine for a PRI patch cord (they are both 4 pair RJ45 straight thru's), the different signal assigments suddenly matter when building a crossover. Therefore the "Ethernet Crossover Cable" can NOT (:eek:) be used as a substitute for a "PRI crossover".

What's more, the PRI crossover cable seems to be a pretty rare item. Most places you ask for it will hear the words "cross over cable" and ask a few times if you want an ethernet x-o. Just say no! (:frown:) You will probably just end up rolling your own. (:wink:)

I avoid crimping my own cables and being left doubting their integrity, so I use regular patch cords but built a F/F cross over box using a 2 port RJ45 housing. IMHO, jacks in a box (:rolleyes:) are easier to handle, see, label, verify, correct and change. It also allows for easier cable swapping for diagnosis and for length and color changes.


For those using a 586A wall type box, here is a picture of a working one wired for a T1 crossover:


WARNING, I believe this image is incorrect, this image is 1,6 2,5 6,1 5,2 ...
all other documentation states 1,4 2,5 5,1 6,2