Phone color coding

[dwellselectric]

I am confused about something. Say you are running CAT 5 in a house for a phone and you use the blue pair for the green and red and use the orange for yellow and black. Now I have been wiring a phone without say putting the sold blue on the green and the striped blue on the red like I might not do the same in the interface box. Never had a problem with it working, now my new boss is telling me that it can't work if the colors are not the same on both ends? How can this be? any thoughts?

 

[480sparky]

Usually, blue with white (or solid blue, if that's the case) goes to the red. White with blue goes to green.

Orange with white (or orange) goes to yellow and white with orange to black.

"It won't work" may mean you terminate the phone jacks, and the telco terminate the at the demarc box, so you end up with polarity being reversed.

 

[e57]

I am confused about something. Never had a problem with it working, now my new boss is telling me that it can't work if the colors are not the same on both ends? How can this be? any thoughts?

Lets just skip calling them colors - as colors can change pair to pair - call the "Tip & Ring" (T/R) - (+/-)

Yes most phones will work..... Not all, and you should correct the practice for the day you come across the one that wont...

 

[dereckbc]

No phones made today I am aware of are polarity sensitve. Only place today where the phones are sensitive today are pay phones, or older analog trunk circuits with wink start signalling connected to antique PBX systems found in a museum :grin:

I might of over looked something, but I cannot think of any service today on POTS that require a paticular polarity since there are no ground start, ring to ground, or party lines left in use any more. Only exception would be a digital PBX for line power, but that will not be a residence POTS. I don't know maybe Bugtussle MO at the Clampete's place of residence.

 

[mdshunk]

I might of over looked something, but I cannot think of any service today on POTS that require a paticular polarity ...

Digital station phones, like Nortel stuff, are quite polarity sensitive. I understand that's not really what we're talking about here, though.

 

[e57]

Long and short of it - it is bad practice.... And yes - even today you will come across the odd phone that will not work. Not long ago I came across a brand new phone - that due to reversed polarity had full function - except for 'ringing'.... Some forms of DSL also have trouble. Premise VOIP lines originating from server equipment as well.... And, your TELCO can tell when you've done it on some equipment they have right in the CO - so if the customer ever calls about any complaint whatsoever - they say "Inside wiring problem" and point the finger at you....

Some more crap on topic.....

In the early telephone years of rotary dial, tip and ring wire reversal was of little consequence. Then came DTMF or Touch Tone. Because the tone generator is electronic, tip and ring had to be in the correct order at any given phone jack in order to be able to make outgoing calls with a Touch Tone phone. If they were reversed in polarity, there would still be a dialtone and calls could be received, but not dialed out. In most phones manufactured in the late 20th century, a diode bridge eliminates that problem. Today, tip and ring reversal is mostly immaterial, except for special circuits including DID (Direct Inward Dialing) trunks, T-1 lines, and ground start lines where the field side ("terminal") equipment--a company's PBX switch, for example--can only function correctly with correct tip and ring polarity.

ref: http://en.wikipedia.org/wiki/Tip_and_ring

media.wiley.com/product_data/excerpt/63/07803474/0780347463.pdf

On page 11 there is a rectifier circuit that corrects polarity - in much the same way AC is converted to DC with a full wave recticifier.

Bad add - just go through....
http://electronicdesign.com/Articles/Index.cfm?AD=1&ArticleID=1539

 

[Rampage_Rick]

Just buy one of these:

The LED will light green if the polarity is correct, red if it's backwards. (If you see orange then someone's trying to call you...)

I think mine cost $5. Then again I have no clue where I put it being that I haven't used it in at least 4 years. Firstly, I've never run into an issue where polarity caused problems (and I do a lot of Nortel) Secondly my TS-44 butt set indicates polarity (...and voltage, and current)

 

[dwellselectric]

Thanks guys for the info:smile:

 

[Rampage_Rick]

I dug through my stuff and found it. It's a GB GTT-200 dual-line tester.

Oh and for future reference, Old analoge quad-wire is the only place you'll find where red is negative (ring = -48V and tip is ground)

 

[anewsom]

i have also ran accrossed a newer phone that wouldnt ring in due to reverced polarity but it was on a voip circute. if my memory service me right it was a uniden cordless phone set.