T! crossover cable

Hi Rich...

I'd be quite surprised if you'd need new cables to move a working DS-1 from one service to another, especially if the same access provider is being used.

But... To make a "DS-1 Crossover cable" wire it like this:

On the "Left" one end of the cable wire pin 1 to pin 5 on the "right" end and pin 2 on the "Left" end to pin 4 on the "Right" end. And vice versa (4 & 5 on the "Right" end connect to 1 & 2 on the "Left" end. (If it makes more sense to you subsitute CSU for "Left" and PBX for "Right"!). Making these connections connects the transmit signal on one end of the cable to the recieve signal on the other end while keeping the tip and ring conductors "straight".

Good luck! Enjoy a fun and safe holiday!

Al

You won't be able to find one in a store, you'll have to make it, or change things around. You may be able to find one on eBay for CCNA's doing testing or the like.

Most likely what he meant is that the tech might have reversed the pairs when they installed your new T1. They frequently don't check to see if their pair polarity is correct on their T-BRD sets when they test them. I know I've had to fix this sort of problem dozens of times when I've been onsite installing routers and such.

A T1 is pined out on an RJ-45 to be receive on pins 1 & 2 and Transmit on pins 3 & 4. This is different pins than what Ethernet uses, so an ethernet cross-over won't work.

You can make your own T1 cross-over cable by simply reversing pin 1 and 3 and pin 2 and 4 end-to-end.

Or, what is probably easier, is to go into the jack, most installer techs use a screw-down terminal jack, move the cable on pin1 over to the one on pin3, and move the cable on pin2 over to pin4.

Then it'll be wired correctly for the future instead of having a special cable that you'll forget about in the future.