These racks and mountings often include RJ48X/S jacks that have been named "smart jacks" because they are equipped with shorting bars that bridge the transmit and receive pairs together when the plug is not inserted in order to keep the circuit alive. There are a few things that need to be considered when extending a circuit from them.

First, the maximum cable length on the CPE side of the network termination card (basically at the "smart jack") is 655 feet. That's 655 perfect feet, as in a cable that is run in a straight line, has no kinks, twists or sharp turns.

Next, this 655 foot maximum length is determined by padding on the network termination card itself. These settings vary from 0 feet to 655, and it must be set by the telco technician when the circuit is installed. Since the telco's responsibility ends at the RJ48 jack, they often don't change the default setting, which is for circuits under 100 feet (don't quote me on that).

Lastly, it is standard practice for the extended circuit's transmit and receive pairs to run under separate cable sheaths. In multi-pair riser cables, they would accomplish this by placing the transmit and receive pairs in separate binders within the cable. ANY form of separation is better than none. In your case, there should be two cables extending this circuit. In the case of multiple circuits, all of the transmit pairs can be in one cable and all of the receive pairs in the other. Shielded cables are even better, assuming that the shields are properly grounded and bonded so that external interference is minimized.

With a single CAT5 cable used as the circuit extension, combining transmit and receive within the same jacket can lead to the circuit actually interfering with itself. This can lead to all kinds of phantom issues that are impossible to trace.

Remember that CAT5 or greater cable is a lot longer copper-wise due to the tight twists in the pairs. 300 feet of CAT5 cable can easily be the equivalent of 500 feet of CAT3. People think that CAT5 cable is "better", but actually in these instances, the added capacitance and resistance are actually hindering things. CAT5 cable was also designed for LAN use, not really for telecommunications. It meets all of the specifications for those networks, but these aren't the same specifications used by T1 technology.

T1 circuit technology was developed more than half a century ago and trust me, these circuits can function just fine over "CAT Zero" cable. Category ratings weren't even developed until the 80s. In prior years, cables were just referred to as 'twisted pair' or not. Telcos terminate their circuits on these cards in order to ensure that despite many thousands of feet of questionable cable, they will meet specs at their jack and not another foot farther. Those network termination cards work miracles in cleaning up any errors that may occur in the outside cable feeding them. In a perfect world, and if it was possible, this card would be installed directly in the customer's suite. Knowing Verizon the way I do, we know that's not likely to happen.

Don't forget that Verizon isn't in a big hurry to make their competitors look good, so they aren't going to jump through hoops to take care of what in your case is a stepchild. The best thing that you can do is to do the best you can on the CPE side of the termination and hope for the best. If you really want to play it safe, get a pair of media converters for T1 circuits and run the extension with a pre-terminated fiber cable.

Ed Vaughn, MBSWWYPBX