atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's T-1 Cross Over Cable

Can anybody tell me if it is possible to reverse Tip and Rings on a T-1 cross over cable and have it still work. Sounds strange, but I am being told it works. Cable in questions is wired:
5-1
4-2
1-5
2-4
I know this isn't standard, but am wondering if it would really work.

Tip and ring (pair polarity) is not significant per-pair, but the placement of the pair is. Your cable illustrated is a true crossover cable. The only other configuration that will work for a T1 is:

1-1
1-2
4-4
5-5

Anything else can't be used on a properly-wired RJ48X jack.

Ed,

I thought the correct wiring would be:
1-4
2-5
4-1
5-2
If you look at Cisco or Adtran's websites the above is what they recommend. So, now I'm really confused based on your reply above.

I always use a standard patch cable (straight through)with no problems.

You can't always use a straight through cable, when you're hooking up equipment which expects to be the user end as opposed to a network end. For example, from the smartjack to my adtran, is straight. From the adtran to my PBX is crossed-over when I punched to the block. To hook up other equipment, I made an adapter out of two RJ45 jacks back-to-back, with the wires crossed. Then I use two factory straight cables to make the final connection.

We have always used a true "Cross-Over" cable when going from an Adtran to a router or switch and have never had any problems. If the router is located in a different area than the Adtran, we run a Cat-5 cable, and terminate one end 568-B and the other end 568-A. This creates a "Crossover" connection between the Adtran and the router, and a standard straight thru patch cord can be used on both ends to patch in to the equipment.

568-A and 568-B will give you an ETHERNET cross over.

For a T-1 cross over, it is 1&2 swapped with 4&5.

If you're going to use 568-B jacks, swap the BLUE and ORANGE at one end.

To add my for instance to Touch Tone Tommy's advice, when we specify a PRI to a Nortel from an SDSL circuit, it is a standard straight through from the smart jack to the router and a standard straight through from the router to the server.

THEN from the server to the Nortel DTi card it is a Telco Crossover, straight through on one end and 1 & 2 in place of 4 & 5 on the other end. You are only using two pairs with pins 1, 2, 4 and 5.