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Sounds of a Step by Step Page

If things are going right, you're looking at a QuickTime sound bar above this text. It should be displayed right on the page, ready to go. This is a little different than the Old Days, say, 1998, when you may have needed to download a sound file first before being able to play it. Wait for the black line to fill before playing. What if nothing happens, even after three or four minutes? Check your hard drive for a file named Stepper1.mov , probably in your cache file. Run a 'Find' utility and find out. You may then be able to run the sound file using another progam, like Adobe Page Mill or an audio program. Or go back to the previous page for sounds in a wav format.

Clicking on the left hand arrow gets it going. Holding down your pointer on the speaker icon raises or lowers the volume. You can play it over and over. Listen for the line finder sound at the beginning. I hope to put up a less compressed version that lets you hear more details. That loud hum, by the way, is the interruptor motor; I will record another version with its noise reduced.

While you are waiting for the file to download, check out a private line reader's response to the above picture, which first appeared in private line Number 5:

Dear private line:

Just received my first issue of private line. Nice little publication you have there. I think I shall be enjoying it very much in the months ahead. A few comments, if I may. They regard the note about the step by-step switch photograph on page 44 of issue number 5. Rather than being "the" step-by-step switch, there are also connectors, frequency selecting connectors, reverting call connectors and toll selectors; the mechanical structure below the relays being the common denominator construction. Actually the switch shown is a line finder as evidenced by the single horizontal wiper just below the ticket tag and the tenth level overrun spring assembly in front of the A and C relays. Depending on subscriber activity, 10 to 20 line finders are mounted on a "shelf". The shelf, along with other "shelves" are mounted on a "bay" or common hardware framework which is 72" wide. The shelf is actually the "bank" multiples at the bottom of the switch (they don't show well in the photo) and the wiring. This is all factory pre-wired and shipped as a unit. It is not unusual to see bays with partially equipped shelves which allow for lower initial capital investment and facilities to accommodate increased future traffic activity. The can cover at the left of the photo contains supervisory relays used for assigning the next finder to answer a call for dial tone.

An interesting feature to me over the years has been that each type of switching system (machine) has had its own distinct characteristic sound signature. In a small rural office step-by-step is characterized by intermittent bursts of staccato reports, 20 or more per second if line finders, several groups of 10 per second as a call is dialed through, followed by silence broken only by soft pulsing of interrupter relays and occasional clicking of manually operated toll ringing relays as an operator in the toll switchboard works a call. It also is interesting to listen to call activity. There will be silence broken by switching of a call. This invites a second call which immediately begets a third call, followed by silence again. And so it goes, sporadic outbursts followed by silence.

A crossbar office on the other hand is a different experience. Listening to a working crossbar office is like being shaken up inside a can of loose bolts. It actually can be deafening, especially in the vicinity of the sender groups or the markers. The crossbar aisles are less noisy, punctuated occasionally by operation of trunk block connector relays at bay tops and occasional soft "tink" sounds as cross-points release. However, the granddaddy of all bedlam was created by a room full of mechanical foreign area card translators, especially on Mothers' Day! And a very different sound was heard by those privileged to witness call-through tests of a No.4 Toll Crossbar machine. These were tests performed by the installation departments on completion of wiring a machine and prior to turning it over to the operating company. Every number that could ever possibly be placed in the machine was called using groups of call test "tea wagons". Any call that failed to complete properly was traced out and corrected immediately. Each tea wagon would present twenty simultaneous calls to the senders. The re lay activity through the office, a city block square in size, had a never to-be-forgotten sound that was like an echo as trunk block relays operated in sequence trailing away to more distant link frame aisles. There would be silence while the tea wagons did their thinking. Then every call would be simultaneously dropped with a gigantic "thud" and then the whole sequence would repeat.

My favorite switching machine sound however was the panel office. If ever there was a machine with (if it can be called that), a "comfortable" sound, it was a panel office. To me, a panel machine was a collection of simply delightful "clinking", "whirring" and "squeak, squeak, squeak" noises. It was by far, the quietest of all the machines. The only noisy areas, like crossbar, were those near sender, marker and decoder bays. Unfortunately, today's generation of central office technicians have never had the privilege of hearing these old machines doing their thing. It's a part of the art that has come and gone. I'm glad I was privileged to have heard them.

With reference to your "Lost In Space" column, attached is a recent copy of the Bell Labs News. In it are phone numbers and points of contact. Hope it is of some help to you. On the back cover you show views of the old "500 Sub Set". Mr. Bill Brander, a retired close friend who lives not too far from here, did the first die drawings for the 500 model when he worked at BTL in Murray Hill NJ.

John W. Sponsler Hampton, NH

Wasn't that a wonderful letter? And again, for more details on stepper operation, go to Michael Spalter's "Strowger Telecomms Page", the place for all things step by step: http://www.seg.co.uk/telecomm (external link)

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