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Wired: 1919

Washington, D.C., circa 1919. "Chesapeake & Potomac Telephone Co. wiring." A behind the scenes look at communications tech some 80 years after the telegraph tapped out its first message. Harris & Ewing glass negative. View full size.

Washington, D.C., circa 1919. "Chesapeake & Potomac Telephone Co. wiring." A behind the scenes look at communications tech some 80 years after the telegraph tapped out its first message. Harris & Ewing glass negative. View full size.


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Messy Work

One thing few people remember about tie and crossbar systems was the amount of copper dust that collected on everything and had to be swept off to prevent shorts.


I'm fairly new to the field of telephony (began in 1993 with the USAF), but I recognized this immediately. The equipment blocks are wire-wrap now and the insulation is PVC; can you imagine the friction from the cloth? I love my craft and its history ... especially since I can take a 60 year old (or older) telephone and it'll still work on today's switch as long as you are able to hit the hookswitch just right or have a tone generator with you.

Step by Step in the Sixties,

In the 1960s I worked in a 60,000-number Step by Step exchange with a frame similar to this one. Wire used on the frame was much thinner by the '60s. The soldering irons were electric, and were caged to clamp onto the rolling ladder to work on equipment inside the rack aisles.

The sloped rolling ladders ran on a single track towards the ceiling and had a level shelf that could be hooked on the steps providing a seat for the CO men to sit on when routining switches. A plug-in 48-volt lamp was provided to see with as you changed wiper blades and cords on the switches, then cleaned and lubricated the stepping and rotating mechanism with a brush and a dark red gooey lubricant.

At 0900, when the business day started, all the Line Finders, Selectors and Connectors went wild, a roar of electromechanical wonder linking subscribers thru magic! Just incredible!! On the day JFK was shot, the exchange pulled 3300 amps.

Three GM Diesels in the basement for emergency power, and a huge wet battery room with acid batteries each about 5 feet tall.

Dial tone, ring, busy, fast busy and out-of-service tones provided by electric constant-speed gear-driven rotating mandrels divided internally by an insulated wall with series of holes drilled through. Mercury circulated through the hole patterns, providing required tone sound to subscriber sets. Carbon brushes rode the polished outsides of the disks as they revolved.

Coin Collectors (payphones) had their own area on the second floor to house the extra equipment for coin collecting/return on the telephone in the field. Most pay numbers began with 00, as in WAlnut 3-0079.

At the corners of each equipment rack were coloured electric lights which lit up when a trouble occurred in the equipment to guide the CO man to the problem. The colours indicated the type of problem.

A large alarm gong with an echo chamber and horizontal suspended tone bars similar to those on a xylophone hit by a vertical "hammer" on a solenoid provided the importance of the trouble tones. Dong-dong-dong slowly for minor problem. Ding-dong, ding-dong for more major problems. These sounds cut through the mechanical roar, and the trouble man was guided to the switch at fault by the corner lights above the racks.

The lead-sheathed cables in the basement below the frame which left the building underground to the area telephones and other exchanges were pressurized to keep moisture out, and gas-type meters recorded each cable's leakage.

On the second floor was the Test Centre, where pairs were tested and temporary Dial Tone Snappers were requested by Installers in the field to get temporary dial tone on a pair. These were put up by the frame men.

Amazing to behold, but, one Crossbar number was in use in the building. The sign of changes to come.

Glad I got to see it, just before the end. 60K numbers, all Step by Step!

"No job is so important and no service so urgent that we cannot take time to perform our work safely" -- Bell System

Horizontal Main Distributing Frame HMDF

I worked on one of these starting in 1968. Looked just the same as in this picture except for the neckties and pants. These guys are doing "pullouts," and they'd better get that wire off the floor before the chief switchman (or the wire chief) sees it!

Wife and I met at the phone company.

On and off the job, we were a twisted pair.

Heaven help you

if you were colorblind !!

I was one too

Worked on the frame in Pac Tel's Melrose office in 1957. It was new at the time, we had gone from step switches to the crossbar type, but the frame was identical. Still had named prefixes then: OLive, OLdfield, OLeander & one more I can't remember.

Step By Step

Frames like these are still very much in use today. Physical copper cabling still enters Central Offices from the outside world where connections from homes and businesses must be cross connected to switching equipment which provides for dial tone and dialing. In this case, the switching equipment would have been step by step, a method which used linefinder, selector and connector switches which pulsed digits on relays to facilitate direct dialing.


But I have a strange craving for meatballs and something.

I was one

I was a frame man for Pacific Telephone in 1958. And the frame looked exactly like this, including the rolling ladder. There was no air conditioning and they didn't allow us to open the windows because they didn't want dirt in the stepping switches. It got a bit sweaty in the summer. You weren't supposed to stretch the wires, but we did. One year of this and I went back to school.

Fast-forward 60 years

Great pic. I used to run wire on frames that looked just like this as late as the 1980s.

Looks familiar

Just like what's behind my computer.

Apparatus on the wall

Looks like a soldering station! Gas pipe, several "irons in the fire" a spool of solder under the table, wire brush. All the necessary tools for a good solder joint!

The Frame Man

You’re looking at a central office frame. The equipment for telephone and telegraph circuits was mounted in tall bays in the central office. The leads for each piece of equipment, the line facilities and test jacks were brought out on the frame. Central office technicians would get orders for new telephone or telegraph circuits, assign the appropriate equipment, make a drawing of the wire connections with the frame location needed to make up the circuit and give the drawing to the frame man. The frame man would run the wires connecting the equipment that made up the circuit through the central office. A technician would then test the circuit for continuity. When all the central offices through which the circuit was assigned completed their work it would be tested end to end and turned up for service.

When circuits were disconnected the frame man would remove (pull out) the wires. The equipment assignments would be cleared for reuse on another circuit.

In this photo it looks like the technicians are pulling out old wires. Climbing that tall ladder all day and pulling wires was tiring work.

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