TELECOM Digest OnLine - Sorted: Re: Bell 607 Dial PBX Cord Switchboard

Re: Bell 607 Dial PBX Cord Switchboard
19 Jul 2006 10:41:59 -0700

TELECOM Digest Editor noted in response to

> [TELECOM Digest Editor's Note: The 607 came out in 1950, and that was
> what we had at University of Chicago (actually a 26-position, broken
> in two groups of 12 positions and one group of 2-positions) when I
> worked there in 1958-62.

This must have been a very interesting installation. I wish I could've
seen it.

I presume this was run in a no-nonsense strict manner like Bell
exchanges. Most PBXs of any reasonable size strictly required the
attendants* to be "Bell trained", that is, have previously worked for
Bell as an operator. It wasn't just knowing how to work the keys and
cords, but also the discipline of handling a high volume of call
traffic without getting confused. Telephone operators were taught to
"overlap", that is, pull up the cord in advance ready for the next
call while you were serving the current one and to use both hands
independently. It was one thing to properly know how to work the
keys, but quite another to do so in high traffic. Pretty amazing to

*Bell called its own people "telephone operators" but called people at
PBXs "attendants" to differentiate. The general public called them
operators. At PBXs "trunks" were lines from the PBX to the central
office while "stations" were lines to extensions. The use of the word
"line" was somewhat discouraged as it was vague. In practice terms
were mixed.

I'd also love to know what Bell charged to rent the switchboard, dial
exchange behind it, trunks, extensions, and other parts. I think back
then everything was a la carte without combo packages. The tie-plugs
you mention were extra. (Did you mean tie-jacks?)

The Eng & Sci history says such big boards were custom designed and
built since there were few customers for such large equipment. Most
PBXs were pretty small and mass produced. I wonder how many 24
position PBXs were in the Chicago area, probably not very many.

> ('test for busy' meant touch the tip of your cord to the sleeve of
> the plug on the board; if you heard a 'crackle' sound of static in
> your ear the line was free and you could use it; if you did _not_
> hear the 'static noise' it meant [and your report to the caller was]
> 'line is busy')

I once read how they designed the circuit to do a busy test, it was
kind of tricky. I don't think the callers heard the click the
attendant heard since it was on the sleeve, not tip or ring. Circuit
design did lots of things with the sleeve part of the connection; in
central offices sleeve tests were used for early billing and ANI.
Small non-dial switchboards of course didn't need a busy test nor did
it work on them. All dial boards had to have them as to multiple
manual boards.

Certain jack strips had in-use lights so a busy test wasn't necessary,
I guess they didn't want to take any chances. This included trunks
and some tie lines. On some boards there was a separate row of
lights, on others a light glowed behind the designation strip.

> The extensions could all dial each other of course

Many dial PBX networks had all sorts of dialing procedures between
sister organizations. Many PBXs had both 3 and 4 digit extension
numbers, for example. Some tie-ins required a prefix code first. A
department store with branches could have a number of tie line codes
between stores and to the main store.

> And yes, it was otherwise a 607 board in terms
> of automatic ringing/flashing-back/ etc.

That must have been a big help to productivity and good service. In
the hospital I was at, the operators weren't too good at checking
supervisory signals. Outside calls got a single ring and that was it;
they were busy taking more incoming calls. They were poor on
responding to flashes for a transfer or assistance request.

Operators served as gatekeepers, outsiders weren't allowed to call
certain extensions, such as patient rooms late at night. All toll
calls had to be dialed by the operator with a toll ticket and time &
charges obtained. Bell would call back with T&C which would be placed
on the toll ticket for internal or patient billing. Calls to incoming
patients were made collect (ie to tell them to come to the hospital);
I thought that was tacky. Again, I believe in those days (1971) every
call was charged at retail, not bulk discounts.

Indeed, I think the hospital was a bit frugal and should've perhaps
had another operator at peak times. They also had many key systems
that didn't have any lights to save a few bucks. The two page
operators handled a lot of traffic and that was the toughest job since
it included keeping track of doctors' coming and going. (The operator
sat with a clipboard scrunched in her lap, quickly squibbling in/out.)
They did take the page operators off the switchboard and give them
Call Directors and a desk and a "meet-me" page plus beepers which
helped somewhat. IIRC, 1 (dial 1) was the staff page (interns,
residents, nurse supervisors) and 8 was the doctor page (all other

I really wish I had taken some high quality photos of that board
before it was moved out, but by the time I got a camera a lot of time
had passed by and no one knew me; would've been awkward just walking
in off the street.

> All the student dormitories, faculty housing and the
> 'International House' (sort of a 'YMCA-like' place on campus) all had
> their own switchboards as well, all of which had extensions from our
> main board _plus_ their own 'outside' 7-digit numbers to use as their
> incoming/outgoing lines.

This was a very common arrangement in many organizations. At our
hospital the x-ray dept had its own PBX and outside number (a modern
Call Director style console).

As you described routing outside calls for a sister unit , some
organizations wouldn't do that to not tie up tie lines; they would
tell callers the outside number and make them dial. At the hospital,
if someone was calling long distance or put up a fuss, they would pass
the call through reluctantly. On tie-lines to a rehab facility, they
had to do some sort of flip -- dialing the extension with the front
cord, then quickly putting in the back cord in a separate jack (the
tie lines had two rows of jacks.) Somehow I don't think their little
flip was a Bell approved practice.

> I think about 1963-64 Illinois Bell decided the entire mess should be
> done over;

Was it really a "mess"? Or was it just labor intensive handling the
high volume of calls? Were hospital and college personnel satisfied
with service or were their complaints of dropped calls, long answers,
trouble getting through, etc? Were there enough trunks and dial
equipment to serve everyone when needed at peak times?

At my hospital during peak times an outside caller might have to wait a
minute before being answered. (Although unlike today the operator was
ready when she did answer and ringing didn't stop until then; today
they answer but put you on hold forever). Patients had trouble getting
an outside line or attendant; not enough trunks for them.

> they got University of Chicago to split the cost with them
> fifty/fifty to install centrex;

I thought Bell rented everything. For a new Centrex, I thought Bell
would charge rent and use that to amortize the cost of the system.
For Centrex, there was the issue of putting the gear at the customer's
location (which meant using up floor space) or at the CO. Presumably
there'd be an "installation charge" and a steep one given all the
lines involved, but still nowhere near the full cost of the new

For the organization like that, there'd be a tremendous saving in
labor costs since so many of the callers could dial directly in
without the PBX attendant. The phone book, letterheads, invoices, and
literature would all list direct dial numbers.

I wonder what the rent difference was for Centrex vs traditional

My hospital clearly needed Centrex but apparently the serving CO had
panel or 1XBar and couldn't support it. It would take some time
before they got ESS (1980s?) and went Centrex. Because of expanding
programs, I think they came close to running out of physical space for
extensions on the face of the board. Again, I wish I could've visited
and taken lots of pictures.

As an aside, the designation strips were printed with the names of
whatever dept it was. Later on changes were made by Wite-Out and
handwritten notations, new strips were handwritten.

Somehow the dial system could decode allowable exchanges and reject
distant ones. People were allowed to dial out to the city and
adjacent suburbs only, any other 7 digit call that generated a message
unit charge was not allowed and no 1+ calls were allowed. How an SxS
dial system manged to do that table lookup (and who maintained the
table as new suburban and city changes came on line) is beyond me.
Maybe the trunks were restricted at the CO by special arrangement.

In the city, when dialing a suburban location that kicked in message
units, one would hear a series of various pitch clicks building the
connection, similar to the clicks on a long distance call so obviously
the CO gear knew one from the other. (For message rate or "limited"
customers, a call used 1 unit but calls were untimed). For surburban
calls, they were timed and the overtime units varied by distance. The
system is still used today for metro area calls.

> [TELECOM Digest Editor's Note: The 607 came out in 1950, and that was
> what we had at University of Chicago (actually a 26-position, broken
> in two groups of 12 positions and one group of 2-positions)

I realized that your 26 position switchboard probably would cost more
to build today than a entire modern full featured dial system for the
5,000 extension organization. It's ironic how technology changes the
cost of things.

In other words, in the old days, until probably around 1975, a manual
cord switchboard was cheaper to build than the equivalent dial system
to replace it. After 1975, electronics made dial equipment cheaper.
The huge drop in the cost of electronics and concurrent growth in
power (look at the cost of logic and memory chips in 1975 vs today)
enabled automatic systems to be everywhere

Manual cord switchboards contained a lot of hardware that would be
expensive to make and assemble today. Every station line required at
least one relay, every cord circuit a few relays, and trunk circuits
several relays. Keys, cords, plugs, and jacks had to be well
constructed of heavy duty materials to withstand heavy use and wear.
The keyshelf and jack strips were a forest of minute complex wiring.
An equivalent modern PBX is stamped out from a few chips in mass

Operator's consoles are stamped out in mass production and instead of
hard wired signals with very specific meanings, LCD and LEDs
controlled by chips provide the info. No mass of wiring.

As mentioned, I do feel some level of service quality has been lost by
today's PBX attendants. They were not trained in the same service
oriented manner as in the past and we all suffer as a result when we
call organizations.

I forgot to mention in my earlier post that the Bell System provided a
lot of freebies along with the switchboard; I doubt any of which is
available today. They would train new operators or offer refresher
courses. (I was so trained by a Bell person). They would monitor
service and offer recommendations. They supplied the furniture.

[TELECOM Digest Editor's Note: University of Chicago and Illinois
Bell/Ameritech always had a very close relationship. I do not know
how much the board itself cost in monthly rent, but I do know that
at least in the 1950-70's era, University of Chicago was the second
_largest_ customer of Illinois Bell; their monthly 'phone bill' was
about a million dollars per month; the 'phone bill' each month was
delivered by United Parcel Service in a huge carton box, consisting
of eight hundred to a thousand small pages. There was only one person
at Illinois Bell who was authorized to make any adjustments on the
account or for that matter even discuss it; University of Chicago was
her sole account, she spent six or eight hours daily working on it.
When there was any need of repair service, for example on the board
itself, a repair person was there in usually 30 minutes.

I recall a _very hot_ Sunday afternoon when I reported for work on the
afternoon shift (3 to 11 PM) with a giant-size paper cup of
Coca-Cola. I came sashaying in a wee-bit late (like two or three
minutes after 3 PM), sat my cola down, relieved the one operator on
duty (despite the fact that we had 26 positions, on summer weekends or
overnight when traffic was very slow there would only be one or two of
us there; we used headsets with _very_ long cords and plugged in at
the spot where most calls came through, then when a 'night bell' rang
with a call elsewhere in the room we just unplugged, walked over
there, plugged in and took the call, etc) ... anyway, I had just sat
down and despite knowing full well the rule and the reasoning behind
from my cola, sat it back down and got busy with something else. I
accidentally moved my arm in that direction, and the big, 24 ounce
paper-cup of cola all spilled down inside the switchboard keys.
Ooops! Board lit up like a Christmas Tree, night buzzer went off, and
it was _very messy_.

I had the presence of mind to immediatly remove myself to a few
positions away where I dialed out to 611 and told the repair clerk
that a cup of 'Coke' had just been spilled in the board. The man who
answered my call asked if I had any electric heater/blower around
there and to set it up near the board so things would start drying
out and 'I will have someone over there in 15-20 minutes'. Sure
enough about fifteen minutes later a man got off the elevator, came
over and looked at it, without saying a word, gave me a dirty look,
and sat down there with his tools, unlocked the cabinet, got inside it
with a little 'pick-like' thing and started scraping around and drying
it out.

I sat at my new position very quietly, very humbly, not peeping a
single word; nor did he speak at all. He sat there about 30-45 minutes
picking away at all the tiny wires inside, occasionally muttering to
himself. He finished his work, put the top back down, locked it in
place, then took a rag and wiped around the metal keys a little bit.
Finally he was finished, put his tools back in his holster and turned
to leave, but he paused, looked at me and said, "You know, if I
mentioned this to Mrs. Parsons (our chief operator) you would get
fired -- be out on your ass! -- as soon as she heard about it." I knew
that would be the case, and thanked him for keeping his mouth shut
about it, which he said he would do (although the ten dollar bill I
had in my pocket also probably induced him since it was a hot Sunday
evening at that point and he had no doubt given up some of his day
coming there to work on it. Mrs. Parsons never heard about it I guess,
at least I never did hear about it. The next day was a day off for me
but when I came in Tuesday one of the operators told me "something is
wrong on that position; the 'action' is not quite right; a lot of
crosstalk, etc, I think Parsons is going to make Bell come out and fix
it or replace it." Oh ... is something not right over there, I asked
innocently. PAT]

Post Followup Article Use your browser's quoting feature to quote article into reply
Go to Next message: Jim Stewart: "Re: Bell 607 Cordboard"
Go to Previous message: DLR: "Re: Caution: Unidentified Callers - VoIP"
May be in reply to: "Bell 607 Dial PBX Cord Switchboard"
Next in thread: "Re: Bell 607 Dial PBX Cord Switchboard"
TELECOM Digest: Home Page