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Posted By: Phone Jack T1 Connectivity - 08/23/07 09:25 AM
My first post . . . mostly a network guy but have been placed/forced into this situation.

I have a T1 smart jack located in a building wiring closet. The company that's paying for it insists on placing their router in their wiring closet and wants the line from the smart jack extended there. Initially someone from my company told them that it would be no problem but they were making the assumption that the RJ45 on the smart jack provided an Ethernet connection and since it doesn't, it makes things a little more , um , interesting.

Long story short, I think I can get it done by doing the following: connect the smart jack to a port on a patch panel in the wiring closet where the smart jack is physically located. That patch panel connects to another panel in another wiring closet via a 100-pair telephone cable (I've got to get to this other closet since it has the connection point to get to the company's own wiring closet). To make this work, I'll use two ports on the patch panel since a single pair from the 100-pair cable is punched down for each port and based on the posts I read, the T1 needs two pair.

From the 2nd closet, I'll have a cable to another patch panel that gets me to a data port in the company's closet. And I'll finish it by having a final patch cable from the data port to their router.

Will this work? What distance limits do I have? I've seen 200 meters by reading other posts and its close but I'm within that.

Would it be better to repunch the ports for the 100-pair cabling to tie 2 pairs to the same port or keep them as they are and split the pairs on the patch cable? I'll be using 568b patch cables to make all the connections.

Any words of wisdom will be greatly appreciated. Thanks.
Posted By: EV607797 Re: T1 Connectivity - 08/23/07 09:40 AM
First, we aren't talking about RJ45's here. That's decades-old terminology. T1 circuits terminate on RJ48X jacks that use a completely unique wiring pattern and hardware.

You need jacks that maintain the RJ48X wiring pattern and appropriate loopback functions. Oh and yes, two pair (transmit and receive) are required.

Depending upon the distance and with the proper jacks, you may be able to go about 200 feet using CAT5e cable with minimal impact. To go beyond this distance, you will need to use cable with separately-shielded 22AWG pairs and have the telco adjust their terminal equipment to compensate for extended distance. They can adjust for distances up to 665 feet.

I really doubt that you'll want to go very far using spare pairs in a 100 pair cable. In doing so, you'll be plagued with various troubles that are just about impossible to pinpoint.
Posted By: Phone Jack Re: T1 Connectivity - 08/23/07 10:42 AM
Thanks for the info . . . it looks like a new cable run is in order since my scenario would need to use the 100 pair cable for a pretty fair distance.

Just for my education, from what little research I've done, it seems that the RJ48X wiring is compatible (maybe that's not the right word) with the 568b I'm used to seeing.

And when you're talking about the jacks you're not referring to the modular connectors are you? That's what I was referring to when I said RJ45 (my bad).

If I understand it correctly, the RJ48X jack provides a loopback even if a cable is disconnected so your advice is to maintain that ability throughout the entire cable run. I'm guessing by doing that, you'd then have the ability to continue to test the circuit regardless of which cable might be disconnected beyond the smart jack??

If there is an article or previous post you could refer me to, I'd appreciate it. I'd like to understand this a little better because a little education can be a dangerous thing . . . again thanks for your help.
Posted By: EV607797 Re: T1 Connectivity - 08/23/07 11:03 AM
You are absolutely correct. The 568B wiring pattern for cords, etc. is compatible with RJ48X circuits. You are also correct about the functionality of RJ48X jacks. The major difference between standards is that LAN wiring uses pins 1,2,3 and 6. T1 circuits use pins 1,2,4 and 5.

The loopback jacks are necessary so that the circuit remains alive regardless of where along the wiring extension that a device is disconnected.
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