ECN Forum Forums General Topics of the Trade General Discussion Area telephone wiring?

Does it matter if the tip and ring are reversed and why? How will the reversal cause a malefunction?

Edward

With most modern equipment, a T-R reversal won't make any difference.

In fact, I've noticed the SBC installers are getting really sloppy recently with tip & ring conections at the drop.

Cliff

Years ago before touchtone sets had "polarity guard" {in-set bridge rectifier} reversed polarity would kill tones generated by the keypad...but that was 20 years ago. [Some businesses would use per-pair reversing switches at the punchdown block to prevent after-hours outbound calls, while still being able to answer inbound calls.]

A lot of older pay phones relied on "ring-ground-start" to bring up a dial tone after the money was inserted. As you might guess tip-ground-start didn't work and party lines relied on polarity to do selective ringing. In today's world, most equipment no longer cares. I still watch it as a matter of habit. right-red-ridge-ring.

The 1A-2key equipment that we used to use in our large facility felt the effects of T&R reversal but I've not heard of any since the upgrades to electronic key and larger systems have gone in throughout the last decade.

[This message has been edited by BuggabooBren (edited 11-24-2003).]

Just to add to what the others posted, "nowadays" it is not as important because of the electronics involved.

One of the symptoms I would hear (on some old phones)of a reversed T&R was that the ringer armature would move with the pulses generated when using a rotary phone. So, somebody would dial and you would hear the number as "dings." The good thing about those old phones is they are very immune to Radio Frequency Interference (RFI), and they were built like tanks--drop one and you might break the floor

I would think that keeping the correct polarity is important for troubleshooting. With the proper equipment, it is possible to tell if either the T or the R conductor has a problem with it, right down to the location of and type of problem. I would imagine if at some point the conductors were mixed up, it would create some confusion.

Then again, I've never done any actual telco-equipment work so this is speculation on my part

There is a great website that has loads of information on troubleshooting: http://www.mccartyinc.com/

P. S. To tell which is which, connecting a test set from ring to ground should draw dial-tone (with a hummmmmmm....) and from tip to ground no dial-tone.

When I was on the Telephone Repair Cust.Svc. desk, we would have callers press their touch-tone pad keys and if we got 'click, click' we knew that it was reversed. Since it's been an eon ago I don't remember exactly how the phone calls were established, either us calling them on the reported line or them calling us but I think they'd report the phone line from another phone and we'd attempt a call to the errant phone which would ring fine and be usable, as Bjarney describes above.

ThinkGood,

Having the calling set's bell make a little jingle when dialing out is called bell tap, or tinkle.

Shalom,

Cliff

In British systems we always maintained correct tip and ring connections throughout.

Party line ringing has already been mentioned. Two-way party lines were once common in Britain, and as well as applying ringing to either tip or ring these also used a ground-start for outgoing calls, each subscriber having a button which he was instructed to press to get a dialtone. One party grounded the ring, the other the tip.

Many old step-by-step switches in both the U.S. and U.K. reversed polarity on the caller's line with supervision. Thus any of the older polarity-sensitive TouchTone pads would stop working once the called party answered.

Just think, had that situation continued, we could have escaped the "Press 1 for...., press 2 for....." frustration that we have to put up with nowadays!

The more enlightened subscribers may have called by pulsing out the number on the hook switch. It would be especially easy if 611 or 114 was in operation in the area.