Talk:RJ11, RJ14, RJ25

Digital vs. Analogue

A British friend of mine refers to RJ-11 as "digital phone cable". I thought it was analogue. Does anyone who knows feel like including either appropriate term in the main article? samwaltz 10:23== kpkkpk, 7 June 2006 (UTC)

There's nothing the least bit digital about RJ11, and it also has very little to do with cable, but many people mistakenly believe that the 6 position modular connector is what "RJ11" means, and that same connector is in fact used by many digital phone systems.

I suppose it deserves mention that RJ11 is about POTS (classic analog) telephone lines, since there are other kinds now. I'll do that. Bryan Henderson 02:44, 24 August 2006 (UTC)

The reason for this is that the standard POTS connector in the UK is the BS-6312 one, to the non-technical eye this looks completely different to the RJ series. OTOH, ISDN uses the RJ-45 connector and ADSL uses RJ-11 both of these are digital and "obviously" very similar to each other. Likewise in the office you're likely to have a "digital phone system" running over the RJ-45 structured cabling; ie another "digital" system on the "digital" connector. So no surprise the entire RJ connector series is seen as "digital" really. 86.16.135.53 10:53, 28 October 2006 (UTC)

We really need to keep RJ11 intact. We just bought a V02 data acquisition system to measure metabolic rates during stress tests. This is pretty state-of-the-art equipment and it uses an RS-232 interface. The best way to drive this from a laptop is to use an RJ11 to RS-232 cable. It won't work with a USB to RS-232 adapter.

Why would anybody use RS-232 on new equipment? jj

1) RS-232 exists for far more devices than USB. The world is not a Window PC.

2) RS-232 is VERY cheap and simple; ps/2 keyboard connectors are cheaper than USB because of this. In fact RS-232 is so simple any microprocessor can use bit twiddling to create one in software.

(Yes I mean any uP, 8051, 6502 and up) 86.16.135.53 10:53, 28 October 2006 (UTC)

PS: no 5 metre range limit either.

3) (or PPS) RS-232 works because it is simple and standard, no configuring ip addresses or installing usb drivers. (example: brand new Cisco router, configure it via RS-232 first so it's on the network, then you can configure it the rest of the way over the network, if needed) --132.20.251.4 05:11, 16 January 2007 (UTC)

It is even worse than the above makes it seem. When serial (RS232) printers dried up and only USB ones were available, I had to add (to a small diagnostic instrument) an ARM processor running Linux just to host a USB driver. Bit like building a whole kitchen to make toast...

I think either all RJxx conectors should be independent articles or merged with modular connector, ZyMOS 18:34, 10 October 2006 (UTC)

DSL

What's going on with the 4 RJ-11 wires with a home voice/DSL line? the wire carries audio, video and a small amount of electricity to power certain items such as security cameras.

RJ11 cable wiring: crossover is standard?

Looking at the variety of RJ11 and RJ14 telephone cables that I have for connecting from the wall socket to the actual phone, most (but not all!) seem to be wired with the pair wiring reversed from one end to the other: pins 3/4 will be red/green at one end and green/red at the other. I am assuming that ordinary telephone equipment expects this. This is different from "RJ45" network cabling, where "normal cables" are straight-through wired, so I think this bears mention on this page (that standard telephone equipment expects a crossover cable) if I haven't just managed to get mostly bad phone cables over the years (in my experience most equipment seems to work fine either way).

Akantha 05:04, 9 January 2007 (UTC)

• That is techincally a "roll-over" cable, where polarity is reversed from one end to the other. A "cross-over" has pairs connecting to different pairs at the opposite end. Yellow-red-green-black on one end and black-green-red-yellow on the other will have the same pairs connected but the polarity changes. I have never encountered any analog telephone equipment that cared about polarity. (if anyone else has, I'd be interested in hearing about it) Audio signals are alternating current as are ringing voltages. As far as digital phones are concerned, it would completely depend upon how it is designed. Some digital signals don't care because they just look at the transition of a signal between high and low, some or none. --132.20.251.4 04:19, 16 January 2007 (UTC)

• • The 2 analog phones of my childhood home would answer and join a call but could not dial if polarity was reversed. These phones were installed in San Jose, California, USA around 1980 give or take a few years. 66.126.83.138 17:40, 17 June 2007 (UTC)Shawn Brown

Pinouts Table

The T/R and ± column in the Pinouts (sic) table conflicts with the information at the Tip_and_ring page. The Tip_and_ring page states that the Tip is the negative (ground) side and Ring is the positive (battery) side of a phone circuit. The Pinout table has "T" (for Tip) being positive (+) and "R" (for Ring) being negative (-). Which is correct? —Preceding unsigned comment added by 70.79.84.121 (talk) 01:51, 20 November 2009 (UTC)

The picture identifying pin 1 of the modular connector is wrong. One arrow points to pin 1 and the other arrow points to pin 6. Both pointers are labeled as "pin 1"... which is physically impossible. —Preceding unsigned comment added by 76.90.211.240 (talk) 23:37, 27 December 2009 (UTC)

The arrows are correct, but the photo is not very clear. The photo shows the connector with the retaining tab underneath (bottom) and with the connector sitting on the cable entry and tab facing away (top). --Tothwolf (talk) 01:44, 28 December 2009 (UTC)

Comparison needed

This article really needs a picture of all three in order to distinguish between them. — Hex (❝?!❞) 19:43, 7 September 2008 (UTC)

Guess what, there used to be one here that was great. Guess someone took umbrage to it. ---Ransom (--67.91.216.67 (talk) 21:35, 23 October 2008 (UTC))