DSL and filters for old phones--question [telecom]

An even better idea is have a DSL Spliter installed at the entry point and run Cat 5 or I/O wire to the DSL modem, that way you don't even need the filters which I found caused more problems then they were worth.

The way Bill did this is the same approach I took, and it really worked out well. A couple thoughts, tho. . .

Remember the phone line to the DSL modem must be connected before that whole-house filter.

They do make whole-house DSL filters, but my telephone company did not provide them when I got my DSL service. Those filters provide a filtered connection out for the house wiring, and an unfiltered connection for the line to the modem.

Filtering the entire legacy phone wiring helps protect the DSL signal from losses due to poor installations or lossy phone wires. I ran into a situation where the yellow wire had been connected to one of the signal wires (red or green) for some reason, and that created an unbalanced condition that acted as an antenna that caused an early solid state phone to become a radio receiver. That probably would be real bad news for a 'normal' DSL installation.

....Bob

iF that's the only phone in the house, why not open it up (tab on the bottom to release the cover) and see if you can't fit the dsl filter inside with a little jerryrigging. Perhaps behind the dial. You can cut the plug off and hard wire it to the phone and put an rj11 plug on the incoming wire to plug into the filter. I think the filters will work in either direction.

mm

My experience with 4 or 5 brief DSL installations that the filters often aren't required. I tried it both with and without them and the voice quality seemed to be the same in either case. I guess they provide them because it some cases they are needed.

Isn't that the standard way "private line" phones were wired from the days when party lines were in existence? As I recall splitting out the 3rd wire and putting a capacitor or a diode or something on it allowed two different ringing schemes to be used (pulsed DC one way for one phone and pulsed DC the other way for the other phone on the same line).

In this area, the yellow wire was connected to ground at the demarc -- and if you had a Princess type phone that needed power for lights, that power was supplied from a transformer and fed along the black wire, using the yellow for return.

Lots of homes had been wired with just 3-wire cable.

You are right on the ringing. Party-line ringing was accomplished by using the 4 possible combinations of pulsed DC from each side of the talk pair (red and green) to ground. But, the yellow should never have been connected directly to the red or green.

In my daughter's house a satellite TV installer plugged a receiver into a phone jack without thinking about a filter. That almost completely killed the DSL signal. Using the whole-house filter idea, that type of thing would not happen.

Someone else here posted that filters aren't always needed. The filters eliminate the strange sounds a DSL signal might generate in a telephone, but with some phones that would not be a problem. That satellite receiver could care less about a noisy line -- it only had to check for a dial tone once a day. Maybe you can put up with some buzzing on an answering machine.

But, the filters also keep some phones and other things from sucking out the DSL signal. Without them, your DSL might still work, but just not work as good as it could.

....Bob

Our esteemed moderator is correct here. At my previous house I did the same thing, but completely in the NIJ box. It was a 6 line NIJ with only one line in use. (the previous owners of the house had 3 lines.) Most of the jacks were "home run" to the NIJ so it was easy to isolate the one going to my DSL modem. I plugged the DSL filter into the line 1 jack and plugged the leads from 2 of the other lines into the DSL & phone outputs, then moved the wireing from the line 1 terminals to the other line's terminals for voice & DSL.

That worked fine for a few years until I needed a service call (for a problem outside of my house not related to my wireing). The tech looked at my filter installation and said "I can do it better than that", and he did. He removed the line 1 terminal block and replaced it with one having the DSL filter built in, moved the wires back to it. Worked fine and was in use until I moved.

took the lead

The Princess phones came along after party lines were all but abandoned, thus the new use for the yellow wire. But indeed, the yellow was used as part of the party line ringing circuit.

Here is a schematic of the Model 500 Bell phone. Note that it has red, green, and yellow wires (and no black at all). The arrow points to the place where the ringer wire had been separated out to the yellow wire during party line service, but for private line service it is merged onto the green wire and the yellow is no longer connected to anything.

Just a historical note--party lines remained reasonably common long after the Princess phone was introduced. Likewise with the Trimline phone, which also had a dial light. Indeed, back in the 1950s where were sets with tiny dial lights on them that needed power.

Admittedly, party lines were usually for more frugal customers who probably wouldn't pay extra for a premium set like a Princess or Trimline.

Today, many local companies don't even offer party line service at all. Some allow existing customers to be grandfathered, but no new customers. I suspect today, in 2010, the number of U.S. party line subscribers is extremely low.

As I understood, a mod to a 500 set was required if the household was on a "different side" of the party line. Households on the 'main side' of a party line needed no modification.

In the Bell System, there were four distinct methods to keep party lines separate, I believe it was a combination of "side" and "bias" (someone else will have to elaborate). I believe bias was only used in four party lines, the more common two-party used 'side'.

Note that the panel switch design included all of this so party lines could each have their own number and private ring automatically.

Rural party lines that exceeded four parties needed coded ringing.

Independent telephone companies often used frequency ringing.

Very interesting diagram. It probably represents what was used in our area.

The party line ringers used a small vacuum-tube type of relay as part of the ringer decoding scheme. I still have a ringer around here in my archives that was left over from the 'old days'. Probably could take another look at it.

Some areas used harmonic ringing instead, where the ringer responded only to a particular frequency, and the exchange supplied a variety of ringing frequencies. I would assume in those cases the yellow wire would not be needed.

But, the important thing was, the yellow wire should never be connected directly to either of the talk-pair wires. In my case, that crossed connection enabled a phone to pick up a 50,000 watt radio station about

....Bob

Oh, we had party line service long after the more modern phones (Princess and Trimline). And, it wasn't because we were frugal -- we were on an 8-party line, and that was all we could get because we were way out in the sticks, almost a mile outside the village limits!

We had to pay more for an 8-party line than those on a 4-party line in the village. When I questioned the phone company on this, the explanation I got was "Eight-party phone lines are more heavily loaded than four-party lines, so we have to provide more telephone poles to hold the lines up." (Please note I put that in quotes! It is NOT my explanation!)

But, we are back to the coded ringing! We have a second number now for a fax machine, so it is like the old days -- one long ring we answer, the two short rings are for the fax machine (or a wrong number).

....Bob

I don't know of any switches in common use that did not provide for party line ringing. However, what you are describing is terminal-per-station operation. Some offices only provided terminal-per-line service, which meant that all customers on that line had the same line number, the distinction between parties being proided by an additional digit at the end, just like W, J, R and M in manual offices. The final digit normally was not set off by a hyphen, as in a manual office, but just included as part of the listed number. So party-line subscribers' numbers had one more digit that numbers of individual lines.

And thus could provide more than 4 partieis with individual ringing. Wes Leatherock snipped-for-privacy@aol.com snipped-for-privacy@yahoo.com

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In the Bell System, two-party line ringing was accomplished by applying ringing between either the ring lead and ground, or the tip lead and ground. Since the ringing was applied *TO* *GROUND*, and one side of the line was left open during ringing, only one party's phone would ring.

The "Ring" party would thus have their ringer connected between the ring lead (the one with -48 v on it during idle conditions) and ground, in series with a capacitor. The "Tip" party would have the ringers in their phones connected from the tip lead to ground, _without_ a capacitor.

When either party placed a call, the CO would briefly reverse the polarity of the line, and test to see if current flowed *TO* *GROUND*; if it did, then the call was being placed by the "Tip" party, which had no capacitor in their phone to block DC flow through the ringer. If there wasn't any current flow when the CO flipped over the line, it was the "Ring" party that would be billed.

In areas with a lot of two-party lines, it was common to have instruments pre-wired with one side of the ringer connected to the red (Ring) lead, and the other side connected to the Yellow wire, with the ringer's center taps wired to the capacitor inside the network assembly.

This arrangement meant that at least 2/3 of installations could be accomplished without needing to open the instrument(s); a single-party line would have the yellow lead connected to green (Tip) at the protector, and a two-party line that was provisioned as "Ring" party would have the yellow lead connected to ground at the protector.

The only time these phones had to be opened was for "Tip" party service, since the installer had to move the ringer input lead to the green (tip) side of the line inside the phone, and short the center taps to provide DC continuity for outgoing party detection. The yellow lead would still be connected to ground at the protector.

Of course, the presence of a DC load on the tip side of every instrument would imbalance the line slightly, but the effect was small and most customers never noticed it given the relatively high resistance of the ringer coils. However, sometimes "Tip" party customers would obtain and connect instruments intended for single-party or two-party ring-side service: although a little experimentation would get the ringing working, those customers didn't know about outgoing-party-detection, so their calls would be billed to the Ring party until that customer complained.

BTW, the "Ringmate" services now offered by most LECs is just good-old-party-line service with a new name on it, although in most areas it is tariffed for *incoming* calls only, with all outgoing calls billed to a single number. This tariff hack allows customers to plug in "generic" phones, and the CO uses coded ringing to differentiate the lines on incoming calls.

Bill Horne

P.S. I never worked on four-party or eight-party lines, and so am not familiar with harmonic or dc-bias systems: in any case, all four and eight party lines I ever came across used coded ringing.

I've had Timline phones in the past that required a transformer for the dial light. Sometime in the 80's we bought a Trimline phone that did NOT require a transformer. It's in our bedroom, the dial lights up, but it does not use the yellow and black wires. I guess it's a newer design that just leeches power from the phone line itself (tip and ring)....? -- Jim

The newer models have light-emitting-diodes (LED's) in the handset, in series with the line.

Bill Horne Moderator

When the Bell System was totally responsible for maintenance, they sought a way to eliminate the transformer and lightbulb since that represented extra work by the installer. Sending out a repairman just to replace a burned-out lamp was seen as very wasteful.

Some years ago Bell Labs Record had an article on LEDs and how they could save money for the Bell System per the above. Using LEDs instead of an incandescent dial lamp in Princess and Trimline phones was one welcome solution. LEDs were also utilized in keysets and switchboards. I think they stuck with lightbulbs in the traditional six-button keysets and even ComKey systems, but newer systems (Horizon, Merlin?) used LEDs.

The old Bell System constantly researched ways to reduce the maintenance cost of station equipment. Indeed, even without Divesture, they probably would've sold off station equipment to the subscribers since the maintenance and installation cost in labor was growing. A big problem for the Bell System in the late 1960s and onward was 'churning'--Americans were moving much more than they used and the Bell System was installing and removing phones much more often than the past. (This also wracked havoc on distributing frames which became overloaded from new jumpers).

Note that even before Divesture the Bell System was trying to get customers to do more on their own, such as with modular jacks and Phone Center Stores, and campaigns to have subscribers disconnect their phones themselves when they moved.

Today of course telephone sets are basically disposable. When they break, toss it and buy a new one. Even wireless handsets.