sundance-communications.com/forum Forums Wiring - Telecom Carriers - Trunks & Services Outside Plant OSP Construction How did they do it?

When "A" in the connector operates "B' in the connector operates. When "B" in the connector operates "C" in the connector operates! Enjoyed the pix, Sam!

Subscriber, Line finder, selector connector.

Ding, ding ding, Bang,bang bang, click click ckick.

Hello. Operator please....

It's almost like morse code.

An MDF just like the one pictured was just taken out of downtown Albany, Ny about 15 years ago. Framemen (that's the guys on the ladders) stopped having to dress like that in the late 50's, but by observing the neatness of the horizontal, I'd say that Station Specialties is correct in dating the pic in the twenties or thirties.

Al

We used to call the pre-carrier units "Concentrator-Identifiers". They worked real well as long as you didn't overload them.

In later years we put similar type equipment in on top of the carrier to squeeze more out of it. Digital Loop Concentrators. TR-303 circuits as I recall. We would run 6 T-1s (144 channels) to a LET (Local Exchange Terminal). Each LET would have 4 groups of 4 T-1s (4 x96 channels = 384 channels) coming out of it , each group feeding an RST (Remote Service Terminal). We would feed a total of either 384 (unexpanded) channels or 672 (expanded) channels out of each DLC.

If you did your trafficking properly, they worked fine.

Sam

Heck, Sam, we didn't call them concentrators....we called them eight party lines! :rofl:

after the last 2 digits are dialed at the connector; ring is sent to the called party and when they answer the "f" relay operates and reverses battery to the calling party to enable conversation to take place thru the condensers. simple huh? but it worked.

This is great stuff guys.....

All I can offer in return is more dumpster info.

There were always 2 things most treasured on our dumpster dive missions: 1/2 spools of cloth covered cable, what looked to be relays (which I now know what they were for), followed by a close third - things that we didn't have the first clue what they were, but looked cool. Also always a lot of burnt out flourescents, which we used to take to a nearby field and throw like javelins, just to watch the explosion as they slammed into the ground. Do that today and you would probably go to jail, or the site would be shut down as an EPA superfund site, I suppose.

Still, although we didn't know it, I guess we were putting a lot of mercury in the ground.

Oh yeah - the downside. Lots of cigarette butts. LOTS. The dumpsters always seemed a lot like big ashtrays. But I grew up in a smoking environment, so no big deal. This would have been somewhere between 72-74.

Anyway I understand a lot more now. Thanks to everyone! I just wished I'd of had a chance to tour one of those buildings when I was a kid, and see all those wires and relays in action.

Oh yeah .. the people that came in and out the back, and saw us rummaging, never gave us a lick of trouble. I think most of them actually got a kick out of watching us.

... other thoughts ...

Although it has sparked competition, which is a good thing... as well as innovation, I wish they would never have broken up the system. Seems to be about 85% back together now.... but it will never be the same. The quality bar has been lowered (IMO), and the focus is now on $, not quality.

But it's a funny thing with technology - people tolerate and accept that their cell phone will drop calls and pay a monthly bill that when adjusted for inflation, probably makes the phone bills of the 50s/60s/70s pale in comparison (But maybe not... I remember seeing the long distance bills.. and as I recall, LDD was something you did only if you had to, under no circumstances were us kids allowed to do it (as if we had a need anyway), or LDD was a pre-arranged deal, something to look forward to. And it was a red alert to get the parents if a LD call came in, purely out of consideration for the person calling, even if you didn't know for sure who they were.

Also people expect their computers to crash at least once a day, and don't give it a second thought. Even VoIP customers (something I'll never be, at least not willingly) accept poor connections, echo, and mangled words from time to time as A-OK. I understand my signal goes digital along the way, but at least it's on a 'private' public network which - to the best of my knowledge - doesn't 'packetize' my voice but simply turns it into 1's and 0's over the fiber, and I suppose for my DSL even the copper, and I don't have to worry about my phones going out with the power, or losing my phone service because a magic box on my premises smokes and dies.

Also with U-verse, it's jaw dropping to me that I get voice, HD video, and data all over one twisted pair of copper, at least for part of the way......

Yet even with all the change, people will not tolerate anything but 100% quality and 0% down time from their wired land line phone, which is a great standing tribute to ya'all.

Thanks for all the info -

Matt

PS: Thanks for all the phots Arthur... that site is now bookmarked... gonna take a week to digest all those.

Ken, Decimonic Ringing? John C. (Not Garand)

Off Topic....there were basic ring to ground with code interruption, ring through an atomic tube to ground, or harmonic ringing to ground (ten party lines). Those are the only type I've ever dealt with.

On Topic.....by using the party line system (even two party in town)it allowed the maximum utilization of OSP over the longest distances. So one cable pair could support more than one subscriber yet it went from the C.O. out to each subscriber.

The Concentrator-Identifier units I was talking about had something like 16 Lines going in to each unit and 16 Terminations at the far end. In between were 8 circuits. When you went off hook at the telset end you accessed one of the available circuits to connect you to DT. Same with an incoming call. As long as no more than half the people were off hook at the same time you were OK.

When the price of T-1s came down and more equipment became available with a T-1 interface Carrier-Identifer went the way of the buggy whip.

Of course the Digital Loop Carrier equipment (that I described earlier) was essentially the same thing - only a grander, digital scale.

It's all about getting more useage out of existing facilities.

Sam