phone lines 2

[peetey]

I have a question about phone line polarity. I know it is refered to as Tip & Ring, but if I have a green and a red phone wire which is + and which is - for correct polarity? What is the AC voltage for a ring, and how many volts DC are on the lines normally? Do you guys find that some installations are polarity sensitive? Is ther a reason they call it tip and ring? Any info on this topic would be appreciated. When I determine + and - which goes to red on a wall jack and which goes to green on a wall jack? Pete

 

[IRstuff]

Were your websearch results inadequate?

TTFN

 

[peetey]

My websearch resulted in conflicting info and no definite statements on anything specific. I'm a meterman by trade and need to know this for installing phone lines which are sometimes polarity sensitive. pete

 

[IRstuff]

Then your best bet is to measure the voltage when you are on-site. But, I would assume that if a phone is working on any line, it has the correct polarity.

TTFN

 

[itsmoked]

Check this document. It should answer yer questions.

http://telecom.tbi.net/phone.htm

 

[Skogsgurra]

From the back of my head:

1 Phones are not polarity sensitive - at least not the European PSTN ones. And I think that that is true for US ones as well.

2 A pulse dialling system (which I think that you are referring to) acknowledges a call by reversing the line polarity. The station does this.

3 You ask why the terms Tip and Ring are used. The simple answer is that the old phone jacks were cylindrical devices with a Stem and a Tip. There was also a Ring between Stem and Tip. The Tip and the Ring were connected to the line and hence the designations Tip and Ring. Ring has nothing to do with Ring Signal. Which one could easily think.

Gunnar Englund

http://www.gke.org

 

[peetey]

Were getting warmer. I see the polarities of the pair, but I need to know if I determine the polarity does the + go to red or green in the phone box jack. I am making the assumption that even though I've got a red and green coming in, it may be reversed. In that case I need to determine polarity (+-) and place it correctly on red and green of the phone jack box. It does not show this at the link but does show good info. Pete...

 

[Skogsgurra]

I say again: Polarity is of no concern. At least not in our PSTN. Just connect and go!

Gunnar Englund

http://www.gke.org

 

[wfowfo]

Assuming from your post that you are connecting a meter for remote interrogation, I highly recommend supplemental surge protection on the phone line.

 

[alehman]

http://nps-vip.net/tester/colors.htm

 

[itsmoked]

peetey; I'm getting the feeling that skogs is correct. Looking at all these links which go into to great detail about the color pairs but always avoid any mention of sidedness of the pairs.

 

[alehman]

If you put itsmoked's link togather with mine, you might reach this conclusion:

tip is + and green
ring is - and red

At my house in the central U.S., I get 48.8VDC with green being + and red -, for whatever that's worth.

 

[itsmoked]

peetey just do yourself a favor and don't be touching either wire when the phone rings... Most unpleasant.

 

[Skogsgurra]

I just did an experiment (it could have cost me a telephone). I changed polarities on the phone line. I than rang my mobile phone from that PSTN phone. No problems. I than phoned my PSTN phone from my mobile. No problems. I left the wires in their new positions.

Gunnar Englund

http://www.gke.org

 

[itsmoked]

House burns... Phone company implicated..

 

[Skogsgurra]

Smoke still inside the box.

Gunnar Englund

http://www.gke.org

 

[fsmyth]

Tip is Ground/Common/0v/Return.
Ring is -48v (battery) and signalling lead.

For a 2 or 4 wire connection, the Tip is green, Ring is Red.
For 3-pair wiring, the Blue/White pair is the first line;
Tip is the group (white) wire for all pairs.

You gotta think like telco: ground is (+), working voltages
are (-), and the top/upper/first/outside terminal is ground.

Polarity is important to you only if you have a 2500 or
similar set (Touch-tone pad). These will not generate a
tone if polarity is reversed. Rotaries do not care.
In the last decade, polarity has become much less important
at the consumer level - most (all?) electronic phones, modems
and such have full-wave bridges in the circuitry.
<als>

 

[peetey]

I think we have the answer I was looking for. We have certain meter modems and line sharing switches that appear to be polarity sensitive. I don't like to be a hack so I wanted to know what I was looking at and be able to talk intelligently about it. Date line July 31 st, prominent engineering forum contributer house is totally destroyed when the polarity of the phone line was reversed. Sources say phone company thought he knew too much and targeted him for elimination. It is thought that ITSMOKED is the name of a high tech Cyber terrorist unit that he was the ringleader of......

 

[itsmoked]

ring or tipleader?

 

[peetey]

Touche!