Telephone Ringers: how & why

The metal fenceposts actually have a fairly low resistance. Unfortunately they're also pretty much grounded...

[snip]

If I recall correctly, a REN=1 has an effective impedance of about 8,000 ohms which results in about 1W of power. This is what we used to estimate the ring generator requirements for the PBX that I used to work on.

I'll see if I can find the Bell Pub that gives the formula for calculating the ringer equivalence number, but I'm pretty sure that 1W for a REN of 1 is about right.

Bob

Besides, I thought that *was* country music.

That shows what little you know about music.

Speak for yourself.

Mine has a sticker on the bottom that says says: BELL SYSTEM PROPERTY NOT FOR SALE and another that says: Sold by: Pacific Telephone Jan 09 1983

It has a dial too.

That was very common, though I don't know if Bell System companies did it or not. When I was in grade school our phone was two shorts, but that was an independant telco, not a Bell operating company. I'm pretty sure that they also used at least one of the above systems and that we did not hear all of the rings. If I remember right there were something like 16 parties on a line...

Even into the 50s there were manual Bell offices.

As I recall, by the end of the 50s there were Independent Company Offices (ICO) that even had their own AMA via their Stromberg X-Y offices, before some of the Bell offices had CAMA in their SXS offices.

The ICs were motivated to upgrade their offices by very affordable government loans. The scale of Bell upgrades was so great there wasn't enough money or manpower to properly meet customer service needs, muchless to relatively keep up with ICO upgrades. In 1956, Pacific Telephone Northwest was split off of PT&T primarily so we could raise Capital to meet our needs. At that time we still had some manual offices. It was sure fun....

After a little internet search, I found this old telephone directory page from Waitsfield and Fayston Telephone Co. in a genealogical site.

The numbers are listed by "line" and "ring". Note the broadcast rings at the top of the page. The line through N. Fayston is line 16, the one I remember.

You laugh but I talked a friend into ISDN. He's 41Kft out but it works 99% of the time, and is many dB quieter than his POTS. It was ...disquieting.. to call him from my 7507 as there would zero line noise and during pauses in conversation, you'd often think the circuit was dead...

Don't you just *love* getting your arm jerked from here to there at 20 jerks per second! Makes the arm feel like it just ran a marithon.

I'm not sure about a CO, but in a typical long distance office the ring bus has no interrupter on it. Straight

105VAC at 20 Hz which doesn't stop and let you off every couple seconds... that is *nasty* stuff.

And then there were the 130VDC + and - battery Ttaps for the telegraph (TTY) testboard. Also Ouch.

I thought that it was weird to see an electronic ring generator for sale in a local surplus store, while the local CO was still all mechanical.

Richard Henry wrote in news: snipped-for-privacy@x35g2000prf.googlegroups.com:

We had a party line until 1980 or so, on our smallish independant phone company. By my time, I think it was only 2-3 customers per line.

The multi-grounding thing was used with the distinctive rings. I do know or old 500 wall rotary set was wired with a ground wire.

That ended in the 50s, when dial phones started. The old man doesn't remember those numbers, but has the same number they first issued with the dial phones.

A fair number of subscribers still had manual service even in the early 1960s. There was so much demand for new telephone service that dial offices needed expansion in addition to manual offices being converted. In addition, even those subscribers who had dial service many could only dial within their own community, any calls beyond their own C.O. required an operator until adequate trunk and tandem exchanges could be built. Another challenge was finding land to build a new dial CO. Bell System magazines from the 1950s show operators and service reps working out of temporary trailers and other like arrangements to meet high demand.

Still another problem in the 1950s was the Cold War and massive defense spending. The Bell System was a major military contractor, for both plain military phones and advanced fire control systems. A lot of Western Electric capacity was tied up on top priority military contracts in the 1950s. This became controversial in the later 1960s.

Whether an office was manual or dial did not affect party line service. Dial service, including ESS, had to provide for it. (In a number of states party line service is no longer offered at all, in a few others it is limited to existing customers.)

The last Bell System manual office was on Santa Catalina Island, cut over to ESS around 1980. The last major Independent manual office was gone a few years later, but some very isolated oddball small switchboards may still exist to this day or lasted until not long ago.

Party lines were once extremely common in cities as a way to save money. In the 1940s a dollar a month was significant, and made the difference for many people in affording a phone line or not. In the

1950s the demand for service was so high that people were forced to have party lines due to insufficient capacity.

There was a Rock Hudson Doris Day comedy film "Pillow Talk" about forced sharing a party line in 1960. That was a common problem back then.

In cities party lines were more just 2 party or 4 party, and normally the ringing was only to the person called. The Bell System used bias and grounding to identify which of 2 or 4 parties to ring, the independents used frequency. In rural areas coded ringing was necessary because of so many people sharing a single line.

In some cases a tiny office would be more economical to automate than having an operator on duty 24/7 to handle occassional calls. The Bell System developed less-cost AMA systems for small offices that weren't as robost as a major city exchange.

Curtis R Anderson wrote in news:jt6Ai.3318$yv3.2942 @trndny01:

I don't know if that was one I had, but I had one that used a sonalert for a "bell". It had a screwed on composite CRT monitor (Electrohome chassis), I later used on a PC-XT with a CGA card with the dual RCA outputs (on the monochrome jack, it worked rather well), and the Y output on a C-64.

Inside the case was about 4 cards on a bus (one with a gold and ceramic UART, and other with memory chips in rund can ICs), and a keyboard sticking out. I also had a different VC terminal, which had the keboard seprate on a ribbon, and the terminal works on two card on the right, and a CRT card, with the PSU and a speaker on the mainboard. I reworked that to be a monitor for another PC-XT system with a Hercules card.

As others pointed out, plenty of telephones with mechanical readers are in service. My office uses literally hundreds of plain vanilla

2500 sets.

Another factor in signalling is the length of the local loop. Several people mentioned PBXs, but the requirements of loops in a PBX are usually much easier than that of a central office (per the Bell System history 1925-1975).

Thankfully all my experiences were with real VT100 and DG D416 terminals.

Better; BTL/WeCo came up with "bridge lifters" -- a way to make parties on 2 diverse cable legs parties on the same assignment.

So they'd be able to keep anyone play for party line service exactly that, and no more....

David Lesher snipped-for-privacy@panix.com posted to sci.electronics.design:

Wow, a lot of interesting history has come to light in this conversation. How about storing it in Wikipedia as well.