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Posted By: pauluk A common telephone connector - 12/21/02 07:32 PM
In view of the thread about adopting a common international power connector, I thought it might be interesting to hear anybody's comments on a proposed world-standard phone jack.

What do you like or dislike about the types used in your own country? Are there any features found in the jacks used in countries that you would like to see adopted?

Would you like to adopt an existing national standard as the norm, or maybe design a new srtle from scratch?
Posted By: C-H Re: A common telephone connector - 12/21/02 07:44 PM
RJ-11 is de facto world standard. I doubt there is any work to introduce something else.
Posted By: Texas_Ranger Re: A common telephone connector - 12/21/02 07:54 PM
I agree with C-H. RJ-11 already has become some kinda standard.
Austrian (and german as well) phone sockets support three plugs, so you don'T have to daisy-chain appliances like for example first you have the answering machine, then the phone. You just plug the phone in the center jack and the answering machine into the right one. Only downside: Some cheap phones and modems don't support this and just block off the other devices. A nice thing that used to be supplied by our PO were the phone cords up to 10m, with extension cords up to 15m available-no more need for cordless phones.
BTW: did you know that a certain model of old US cordless phone could be overheard with a standard FM radio?
Posted By: SvenNYC Re: A common telephone connector - 12/22/02 01:43 AM
I am ashamed to say that the USA is the one that started with the foolish RJ-11 plug/socket system.

Before the RJ-11 system we had a 4-pin jack (with one pair of pins spaced slightly wider than the second). These were little cubes measuring 1.5 inches on each side...so not exactly compact. But they were robust. They very rarely broke.

The benefit of the RJ-11 is that it's compact enough for jack panels...like behind a computer on a modem, a patch panel, etc. Also once it "clicks" into place, it stays there and doesn't fall out (unlike the 4-pin plug which can slip out)

But for a household extension where you may have sockets in each room and may move the unit from the kitchen to the bedroom it is not very good. The little locking tabs break off or become weak. And once this happens, the plug is useless. Either replace the entire cord or buy a crimper tool to snap on a new plug (after cutting the old one off, effectively slightly shortening the cord). The old 4-pin jacks had screw terminals for each conductor.

Before the 4-pin plug, telephones were hardwired using a little square box on the wall (with 4 screw terminals inside the cover). Next time I have access to a graphics terminal I will look for a picture and post it. I think South Korea still uses the 4 pin.

Colombia and Venezuela used to use a 2-round pin plug/socket very similar in dimensions to a Europlug!!!!

Imagine the confusions this caused for visiting European tourists plugging their shaver into the telephone box. Now most phones sold in Colombia/Venezuela come equipped with RJ-11 plugs and the corresponding jacks are standard in new construction. You can still get the old two-pin system...but it's mostly old-work/replacement.
Posted By: Hutch Re: A common telephone connector - 12/22/02 02:09 AM
Sven said...

"Imagine the confusions this caused for visiting European tourists plugging their shaver into the telephone box."

It would be even more spectacular the other way around! [Linked Image]
Posted By: Bjarney Re: A common telephone connector - 12/22/02 02:43 AM
The RJ-powered stuff sounds hilarious, but it's really been done!
http://www.sandman.com/telco.html

Part Number: TLS9A “TELCO POWERED™ RAZOR”
Posted By: Trumpy Re: A common telephone connector - 12/22/02 03:03 AM
Paul,
If a RJ-11 connector is pretty much standard,
why then, do we have connectors like the RJ-45?, or am I getting mixed up with Data plugs? [Linked Image]
Posted By: pauluk Re: A common telephone connector - 12/22/02 01:49 PM
The American modular plug has become the de facto world standard, but there are complications, as not everywhere which has adopted it wires the jacks the same way. Ireland uses it now, but the line is always wired on the outside pair (what would be the yellow/black pair in the U.S.) and they use one side of the inner pair as a bell feed in the same manner as U.K. wiring.

Although in general I like American NEMA power connectors, I have to side with Sven on this one and say that I don't like the modular telephone jacks at all. The plastic clips break off too easily, and they're not at all easy to use for anyone with limited dexterity in their fingers. The old 4-prong jacks were far superior in my opinion (BJ will know from another forum that I've just recently been searching for a source of these!)

Another point: The modular jacks and plugs are used at the telephone end of the cord as well. That means that if one end of a cord is connected to a phone line there will be exposed voltages (up to 50V DC and 90V+ AC ringing) on the other end, easily touched.

Although the U.K. has its own design of modular jacks (just as bad if not worse than the U.S. types, I have to add), we are seeing the U.S. modular plug at the phone end used here as well now. In some cases, the latch clip is shortened so that the "live" end can only be removed by using some sort of tool (e.g. a very fine-bladed screwdriver).

Trumpy,
Strictly speaking the RJ designations refer not to the plugs/jacks themselves, but rather to the way in which they are wired. The RJ means Registered Jack, and the numbers were standardized by AT&T/Bell under their USOC system (Uniform Service Order Code).

RJ-11 just happens to have stuck as the name because this is the wiring arrangement for a standard single-line jack as used in most domestic installations.

The same plugs/jacks can be used for other arrangements. For example, a two-line system (line #1 on red/green, #2 on black/yellow) is properly called RJ-14.
Posted By: djk Re: A common telephone connector - 12/26/02 06:03 AM
Just to correct you on a previous point re: Ireland's phone sockets.

P&T (now sold off and called Eircom) introduced RJ11 as the standard jack in Ireland in the late 70s/early 80s during their first phase of digitalisation & upgrading of the network.

It's wired like the US with the signal being carried on the centre two cables. If you plug a US phone/modem into an Irish socket it will work.

The other contacts may not necessarily be used for the same purposes as the US though.

this link gives the full official specs: http://www.eircomlab.com/pstn_pub/pstn.pdf

There was a 3rd wire bell configuration in older installations but it hasn't really been used for a long time. Some configurations also exsist that use the outer terminals on the RJ 11 to trip out other sockets during a call. I'm not sure how it works exactly.

Touch tone/modern ringers have been the norm in new installations since the early 80s. Older installations would have used "headphone style" jacks or have been hardwired.

Using UK specified phones in Ireland:

Generally BT branded phones in particular use RJ11 connectors on the back of the phone that carry the signal on the outer two pairs. In order to use them you generally need to use a BT to Irish adaptor with a capacitor in it. (they're small and cheap and readily available)

Other UK equipment can be used simply by plugging in a normal Irish phone cord in place of the BT style one. 3rd wire ringing requires the adaptor with capacitor however.

Caller Display is also different. Eircom uses a long first ring to activate caller display equipment where as BT inverts the line polarity.
Posted By: pauluk Re: A common telephone connector - 12/26/02 11:44 AM
Hi there DJK, and welcome to ECN!

I stand corrected on the Irish jack wiring. [Linked Image] I was working from memory of a document I saw a good few years ago -- Obviously my memory wasn't good enough!

The link you provided has a lot of interesting details. From the diagram on page 5, it appears the bell feed is wired onto pins 2 and 5 of the jack (i.e. what would be both sides of the black/yellow pair in America). If this is standard, then the UK/RoI adapters shouldn't need their own capacitor, just wire (UK-Eire) 2-4, 3-5, 5-3 and it should work.

Interesting that the standard wiring also parallels the line to pins 1 and 6. You mentioned equipment seizing the line (e.g. an auto-dialer). Looking at the diagram, my guess would be that such equipment takes the incoming line on 3/4 and returns it on 1/6. All that would then need to be done is to cut the two links at the master jack and the unit can cut-off the line to all other jacks.

By the way, it took me a while to get used to that single-frequency 425Hz Irish dial tone when I was over there. It sounds just like a British number-unobtainable tone!



[This message has been edited by pauluk (edited 12-26-2002).]
Posted By: djk Re: A common telephone connector - 12/26/02 04:28 PM
There seems to be 2 different types of UK > IRL adaptors on the market they're both very small white boxes with an RJ11 on a 4cm cable and BT socket.

I'd suspect that the cheaper ones just connect the 2 line cables to the correct pair on the BT socket ignoring the ring wiring.

The more sophisticated version with its own capacitor is prob. better able to cope with any standard RJ11 sockets carrying the line on the centre pair. It would work fine in the USA, Ireland, Spain or anywhere else.

Some of the circuitry in the Irish sockets is used for automatic line testing. Irish Alcatel and Ericsson exchanges seem to run a regular overnight test cycle presumably to ensure that the loop is intact / working. We had DIY wiring hooked up in the US style and at about 3am every night all the phones would ring once!

As for the dial tones etc. The Irish network didn't really follow the same development pattern as the UK and used different equipment manufacturers to BT. Many of the tones and codes would be more like France than the UK

Originally most of the automatic switching was based around Ericsson ARF crossbar, more like scandinavia/other parts of europe. in the UK it would have been stowger step-by-step & various british systems.

from 1981-1985 all of the older generation equipment was removed and rapidly replaced by one of two digital switches ; Alcatel E10 and Ericsson AXE, some of the local crossbar switches installed in the 1970s remained through the 1980's but were relatively sophisticated and "parented" by the nearest digital switch. By about 1990 they were all replaced. The trunk network was fully digital by the mid-80s though. At the time telecommunications investment was seen as absolutely vital to developing the economy.

You'll notice a lot of french features in the system.
Dial tone, progress tone (bebebebe) if the system is waiting for a call to switch (e.g. phoning a mobile / abroad)

minitel was even introduced in the 1980s although it flopped rather badly.

even the first generation cardphones were identical to some of the France Telecom ones.

Eircom's audio samples of network tones probably from an Alcatel E10 switch: http://www.eircomlab.com/audio/narrowband.htm
Posted By: djk Re: A common telephone connector - 12/26/02 07:47 PM
Sorry about the double post! I must have clicked submit reply twice [Linked Image] opps!
Posted By: pauluk Re: A common telephone connector - 12/27/02 08:32 AM
No problem, I've deleted the duplicate.

I hadn't realized that crossbar switching was used so widely in Ireland. I'd always assumed that SxS would have been the mainstay of Irish telephone exchanges, as it was in Britain. A wrong assumption of my part, as Eire was independent by the time automatic switching was widely installed.

Unlike the U.S. and some other countries, Xbar never really caught on in a big way in the U.K. There were a few local exchanges that adopted it, often as trials, but it was largely confined to large tandems. In many areas the local central offices went straight from SxS to TXE (Electronic), or even from SxS to System X (digital).

Do you know when Irish STD was introduced?
Posted By: djk Re: A common telephone connector - 12/28/02 02:54 AM
The history of the telecommunications network over here is a little different.

There were some SxS exchanges in the old P&T network but as far as I'm aware they were confined to local switching and would have been of a very old vintage dating back to the 1930s. There were definitely a few in Dublin and possibily in Cork etc.

Ericsson ARK and ARF crossbar systems seem have made up most of the network in the 60s and 70s though. I don't think we ever had any electronic (non-digital) switches.

The upgrade to digital appears to have followed this route:

SxS, any remaining manual and other switches went straight to Alcatel E10 digital switching in the early to mid 1980's

Ericsson ARF switches seem to have had an upgrade path to AXE digital switching so sites that were ARF seem mostly now to be AXE.

It works out that 50% of the exchanges are Alcatel E10 based and 50% are Ericsson AXE 10 based.

As for the backbone of the network I'm not 100% sure what's used for major trunk switching although I know that they only use Ericsson and Alcatel switches. Recently eircom has invested pretty heavily in "Ericsson Engine" . VPN, 1800 etc and Chargecard is all AXE based.

As for STD it was available for many years between major population centres but some very remote spots would have gone straight from manual switching to AXE or E10 in the early 80s so I guess that 100% nationwide STD didn't become available until then.

If you look around the countryside here you'll see small prefabricated green containers with airconditioning units on top (usually near a post office). They contain an Alcatel E10B that would have replaced manual switching directly!!

The Alcatel E10 (identical to most of France Telecom's network) and Ericsson AXE switches have been pretty heavily modified and upgraded over the years so they're still pretty much cutting edge and provide the full raft of services.
Posted By: pauluk Re: A common telephone connector - 12/29/02 02:16 PM
Thanks for that -- Interesting history. I've never been able to track down much detailed information about the development of the Irish telephone network.

Small villages in the U.K. were often served by a GPO-designed UAX (Unit Automatic eXchange), a small SxS switching system housed in a "cottage" style building.

In places which finally outgrew the UAX you often see a larger early-1970s exchange housing TXE within a few hundred yards of the old building. The old UAX buildings are still there in some villages, serving as small homes, doctors offices, etc.

For those unfamiliar with small English villages, let me point out that most UAX systems had only 3-digit local numbers and even by the end of the 1970s some of these had assigned numbers only in the 2xx and 3xx ranges, i.e. less than 200 subscribers!

By the way, DJK, which part of Ireland are you in?
Posted By: djk Re: A common telephone connector - 05/12/03 01:37 PM
Here's a full explanation of BT versus Eircom wiring and what happens when you plug a UK modem into an Irish phone socket ... (no dialtone)
http://members.toast.net/leslie/testpage/wiring.htm

Thankfully WiFi (Airport/WaveLAN etc) should put an end to all this stuff as more and more hotels and public spaces get wireless LANs installed
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