Voice over 568A/B

Hi,

I've got two RJ45 jacks connected by a long run of CAT5e, with the jacks wired 568A (but A vs. B shouldn't matter which for present purposes). If I want to run three voice lines over this, will I encounter problems if I run the 3rd line on pins 2 and 7, even though this doesn't correspond to a single twisted pair?

The deal is that I've got Cat5e jacks in a bunch of rooms, wired 568A. I want to be able to run 3-line voice over this, but I want to be able to plug a three-line phone plug directly into the Cat5e jacks, and, being

6-position, these plugs obviously require that the third line be on pins 2 and 7.

Will there be crosstalk or other issues if I'm not running the third line on a single twisted pair? For that matter, what if I ran, in addition, a fourth line on pairs 1 and 8?

Thanks! David Gordon

Reply to
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There might be some alien crosstalk from any parallel run cables. Worse will be the 60 Hz hum the split pair will pick up.

Pins 1 & 8, you mean. A recipe for crosstalk.

The easiest solution is a splitter box -- 8p8c plug 568A on one end, surface mount box with 6p6c jack on the other. Or special station cords. Chop the 6p6c USOC plug, crimp 8p8c 568A. MARK!

-- Robert

Reply to
Robert Redelmeier

If you don't use 1 and 8, you will probably be fine, if the cable isn't too long. Maybe less than 50m.

For long distances, such as your house to the central office of the phone company it must be a properly twisted pair.

Oh, you probably shouldn't run a modem on that cable. The signal level is high enough that crosstalk is much more likely.

Of course if only one line is being used at a time you shouldn't have any problems. There is a slight possibility of 60Hz (and harmonics) pickup, so you should try to keep it away from power cables.

-- glen

Reply to
glen herrmannsfeldt

The reason for using twisted pairs, is to reduce interference and crosstalk. Whether or not you have a problem, depends entirely on your situation, taking into account cable length, noise sources etc. Bear in mind, that for many years phones were connected using untwisted pair, right out to the cable on the street. And back in the days of open wire lines, the pairs often went for many miles, without a twist.

That said, I wouldn't want to plug a 6 conductor plug into an 8 pin socket, due to mechanical issues. So either change the connector or make an adapter.

Reply to
James Knott

wrote in news: snipped-for-privacy@comcast.com:

You're probably better off getting a RJ45 to USOC converter:

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Reply to
Anon-E-Moose

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