EXchanges (was: area code named beer) [telecom]

50 views
Skip to first unread message

Neal McLain

unread,
Sep 13, 2011, 7:46:24 AM9/13/11
to
Joseph Pine <josep...@invalid.invalid> wrote:

> Date: Mon, 12 Sep 2011 17:54:51 +0000 (UTC)
> To: reda...@invalid.telecom-digest.org
> Subject: Re: area code named beer

> Neal McLain <nmc...@annsgarden.com
> wrote in
> news:d004cb5b-0868-4ad9...@x12g2000yql.googlegroups.com

[snip]

> The Telephone EXchange Name Project website has a lot of
> material on the subject of exchange names, which might be
> of interest.
> http://ourwebhome.com/TENP/TENproject.html

And in New York...
http://ourwebhome.com/TENP/Times.html
http://tinyurl.com/5r7o246
http://tinyurl.com/6ke8xp2

Neal McLain

HAncock4

unread,
Sep 13, 2011, 12:59:04 PM9/13/11
to
On Sep 13, 7:46 am, Neal McLain <nmcl...@annsgarden.com> wrote:

>  > The Telephone EXchange Name Project website has a lot of
>  > material on the subject of exchange names, which might be
>  > of interest.
>  >http://ourwebhome.com/TENP/TENproject.html
>
> And in New
York...http://ourwebhome.com/TENP/Times.htmlhttp://tinyurl.com/5r7o246http://
tinyurl.com/6ke8xp2


As an aside, in some cases NYC had _8_ digit phone numbers, such as
HOllis 5-10254. A manual exchange could have 10,500 numbers. Also,
if the phone number had a party line suffix, eg. HOllis 5-9242J, the J
was dialed, too. Literature on the panel exchange in NYC confirms the
registers could hold and pass 8 digits. I don't know if that applied
in other big cities.

When calling from a dial exchange to a manual exchange, the desired
number appeared on a display panel in front of the manual operator.
She merely plugged into that number.

Manual service continued in NYC until the early 1950s. A late 1940s
telephone strike steeply reduced service to manual exchanges--the
public was asked to make emergency calls only.

In the early 1950s, NYC subscribers could dial 'toll' calls in Long
Island instead of going through the operator. Instead of being billed
10c or 15c for such calls on an itemized basis, the message unit meter
was incremented accordingly for distance and time (the meters already
existed to do that for local calls). Some subscribers complained
about the loss of itemized billing, but it undoubtedly saved the phone
company a lot of clerical processing.

Thor Lancelot Simon

unread,
Sep 16, 2011, 12:18:17 AM9/16/11
to
In article <0689dcce-3315-43ce...@m5g2000vbm.googlegroups.com>,
HAncock4 <with...@invalid.telecom-digest.org> wrote:
>On Sep 13, 7:46 am, Neal McLain <nmcl...@annsgarden.com> wrote:
>
>As an aside, in some cases NYC had _8_ digit phone numbers, such as
>HOllis 5-10254. A manual exchange could have 10,500 numbers. Also,

What happened to these numbers when long distance direct dialing was
implemented? Were they really all renumbered?

>was dialed, too. Literature on the panel exchange in NYC confirms the
>registers could hold and pass 8 digits. I don't know if that applied
>in other big cities.

"The" panel exchange?

I don't disbelieve this but I would certainly like to see some references.

--
Thor Lancelot Simon t...@panix.com
"All of my opinions are consistent, but I cannot present them all
at once." -Jean-Jacques Rousseau, On The Social Contract

Wes Leatherock

unread,
Sep 16, 2011, 9:54:55 AM9/16/11
to



--- On Thu, 9/15/11, Thor Lancelot Simon <t...@panix.com> wrote:

> HAncock4  <with...@invalid.telecom-digest.org>
> wrote:
> >On Sep 13, 7:46 am, Neal McLain <nmcl...@annsgarden.com>
> wrote:
> >

> >As an aside, in some cases NYC had _8_ digit phone
> numbers, such as
> >HOllis 5-10254.  A manual exchange could have
> 10,500 numbers.   Also,


> What happened to these numbers when long distance direct dialing was
> implemented? Were they really all renumbered?

>> was dialed, too. Literature on the panel exchange in NYC
>> confirms the registers could hold and pass 8 digits. I don't
>> know if that applied in other big cities.

> "The" panel exchange?

> I don't disbelieve this but I would certainly like to see some
> references.


I remember reading about this many years ago, probably in Bell Labs
Record at the time. The devices at the manual end offices were called
Panel Call Indicators (PCI). Somewhere I remember one of the
illustraions was of the ir use in New Orleans, in addition to NYC, of
course.

I have no information on 8-digit numbers or party line suffixes,
except to note that party line suffixes were very common in manual
offices of all sizes, including magneto exchanges.

Wes Leatherock
wlea...@yahoo.com
wes...@aol.com


HAncock4

unread,
Sep 16, 2011, 10:24:37 AM9/16/11
to
On Sep 16, 12:18 am, t...@panix.com (Thor Lancelot Simon) wrote:

> >As an aside, in some cases NYC had _8_ digit phone numbers, such as
> >HOllis 5-10254. A manual exchange could have 10,500 numbers.
>
> What happened to these numbers when long distance direct dialing was
> implemented? Were they really all renumbered?

DDD required that all subscribers have a uniform ten digit number--
three digit area code and seven digit local number. In 1950 a great
many subscribers in smaller towns and cities had phone numers with
three, four, five, or six digits, and all had to be converted to seven
digits. This was a major undertaking that took years to complete.

Those subscribers with an eight digit number, be it 2L-6N or a party
line suffix, also had to get new numbers.

>> ...was dialed, too. Literature on the panel exchange in NYC
>> confirms the registers could hold and pass 8 digits. I don't know
>> if that applied in other big cities. >" The" panel exchange? I
>> don't disbelieve this but I would certainly like to see some
>> references.

The Bell Labs history volume 1 (op cit) mentions that manual exchanges
had the capacity for 10,500 digits. Also, they show the interface
panel for the inward B operator having eight digit capacity, either
the leading 1 or a party-line suffix.

Around 1930, New York Telephone prepared a booklet from a lecture
describing the panel exchange in use in NYC, and this also notes the
eight digits. Unfortunately, I don't have a title nor know how it can
be found on-line.

I've heard that NYC phone books circa 1950 had listings showing eight
digits. Some day I hope to visit a NYC library and look up such a
book (they do have them); I'm particularly curious to see the dialing
instructions.

There were classified ads in the NYT of that era showed an eight digit
number.

Thor Lancelot Simon

unread,
Sep 16, 2011, 7:15:38 PM9/16/11
to
In article <8fe68be8-b2cf-4d9a...@l4g2000vbv.googlegroups.com>,
HAncock4 <with...@invalid.telecom-digest.org> wrote:
>On Sep 16, 12:18 am, t...@panix.com (Thor Lancelot Simon) wrote:
>
>> >As an aside, in some cases NYC had _8_ digit phone numbers, such as
>> >HOllis 5-10254. A manual exchange could have 10,500 numbers.
>>
>> What happened to these numbers when long distance direct dialing was
>> implemented? Were they really all renumbered?
>
>DDD required that all subscribers have a uniform ten digit number--
>three digit area code and seven digit local number. In 1950 a great
>many subscribers in smaller towns and cities had phone numers with
>three, four, five, or six digits, and all had to be converted to seven
>digits. This was a major undertaking that took years to complete.

Not such a major undertaking. In roughly 1980 I lived in a rural area
of New York State that still had 4 digit dialing. Extension to a
_longer_ number can be done automatically -- it is fully deterministic,
you are just adding predetermined digits.

My number was 687-XXXX for external purposes, but for in-town callers,
simply XXXX would do. The "687", obviously, was just added onto the
front when numbers went to 7 digits -- and there were towns near us
with switches still configured to allow 3-digit dialing, which had had
four digits prefixed to the front, too.

However, there is no such mapping from longer numbers (8 digits) onto
shorter numbers (7 digits). Since New York City got only one area
code in the original direct-dial plan, if there were really 8 digit
numbers in circulation, some subscribers' numbers would have had to
be completely changed, not just extended. This is what I am a little
skeptical about.

HAncock4

unread,
Sep 16, 2011, 9:57:33 PM9/16/11
to
On Sep 16, 10:24 am, HAncock4 <withh...@invalid.telecom-digest.org>
wrote:

> DDD required that all subscribers have a uniform ten digit number--
> three digit area code and seven digit local number.  In 1950 a great
> many subscribers in smaller towns and cities had phone numers with
> three, four, five, or six digits, and all had to be converted to seven
> digits.  This was a major undertaking that took years to complete.

P.S. Many times the "conversion" was accomplished at the same time a
town was converted from manual to dial, which was a major effort in
those years. Subscribers had to get used to a new phone number and
billing routing records had to be all changed, but there was no
equipment modification.

However, towns that were already dial had to be converted to be 7D.

In step-by-step offices this often meant adding a "digit absorbing"
selector. Say a town had five digit numbers, 5-xxxx and 6-xxxx and
the town was to become 345-xxxx and 346-xxxx. The switch would simply
absorb the initial 3 and 4. This meant that people within the town
would continue dialing five digits as they did before, only outsiders
needed all seven. In many small towns in isolated areas five digit
dialing continued well into the 1970s. It ended when more exchanges
were added as population grew.

I don't have any statistics, but I suspect DDD was not offered very
widely in the 1950s because the company was too busy expanding toll
line capacity and converting local exchanges to dial. I _think_ the
Bell System was about 50% dial at the end of WW II, not sure of the
percentage in 1960. Anyway, the first step in providing DDD was to
providing operator direct dialing, which sped up call handling. That
meant adding toll trunk signalling systems for ringing and supervision
which was an effort in itself. (That signalling protocol would be
compromised later on by the "blue boxes".)

Even in the 1980s with DDD and TSP widespread, from time to time
operators still 'built up' toll calls by calling intermediate toll
centers and establishing the connection the old fashioned way.
Likewise, they also wrote charge tickets instead of AMA.


Other local exchange items that were necessary to provide DDD were
increasing the sender length in #1 crossbar and panel exchanges to
hold 10 digits, providing an 'exit' link in step by step exchanges,
and providing AMA (automatic message accounting) with automated or
operator calling number identification (ANI or ONI). AMA was
installed either in the local exchange or at a tandem or toll
switching office.


Would anyone care to comment on how all this stuff is handled by
modern exchanges today? Can a long distance company operator still
"build up" a call manually? Are there still long distance company
network managers watching their system for overloads and problems? Is
there still a big AT&T network control center in Bedminster? Thanks.

[public replies, please]

Wes Leatherock

unread,
Sep 17, 2011, 10:35:45 AM9/17/11
to

--- On Fri, 9/16/11, Thor Lancelot Simon <t...@panix.com> wrote:

> In article <8fe68be8-b2cf-4d9a...@l4g2000vbv.googlegroups.com>,
> HAncock4 <with...@invalid.telecom-digest.org> wrote:

[snip]

> >DDD required that all subscribers have a uniform ten digit number--
> >three digit area code and seven digit local number. In 1950 a great
> >many subscribers in smaller towns and cities had phone numers with
> >three, four, five, or six digits, and all had to be converted to seven
> >digits. This was a major undertaking that took years to complete.

Seven-digit numbers were required for operator toll dialing, too. Operator
toll dialing was already widespread before the first DDD was offered to
subscribers.

> Not such a major undertaking. In roughly 1980 I lived in a rural area
> of New York State that still had 4 digit dialing. Extension to a
> _longer_ number can be done automatically -- it is fully deterministic,
> you are just adding predetermined digits.
>
> My number was 687-XXXX for external purposes, but for in-town callers,
> simply XXXX would do. The "687", obviously, was just added onto the
> front when numbers went to 7 digits -- and there were towns near us
> with switches still configured to allow 3-digit dialing, which had had
> four digits prefixed to the front, too.

Generally the switch was configuired to accept the full seven-digit
number on local calls, too, but was not required on local calls.


Wes Leatherock
wlea...@yahoo.com
wes...@aol.com




Neal McLain

unread,
Sep 17, 2011, 11:14:40 AM9/17/11
to
Thor Lancelot Simon in Message-ID: <j50lap$38p$1...@reader1.panix.com>,
quoting HAncock4 <with...@invalid.telecom-digest.org>, wrote:

>> DDD required that all subscribers have a uniform ten digit
>> number--three digit area code and seven digit local number.
>> In 1950 a great many subscribers in smaller towns and cities
>> had phone numbers with three, four, five, or six digits, and
>> all had to be converted to seven digits. This was a major
>> undertaking that took years to complete.

> Not such a major undertaking. In roughly 1980 I lived in a
> rural area of New York State that still had 4 digit dialing.
> Extension to a _longer_ number can be done automatically -- it
> is fully deterministic, you are just adding predetermined
> digits.
>
> My number was 687-XXXX for external purposes, but for in-town
> callers, simply XXXX would do. The "687", obviously, was just
> added onto the front when numbers went to 7 digits -- and
> there were towns near us with switches still configured to
> allow 3-digit dialing, which had had four digits prefixed to
> the front, too.

I agree with Hancock4 -- it was indeed a major undertaking.

In the example you cite, the situation was straightforward: simply
adding 687 worked because there were no local numbers beginning with 6,
7, or 8, and because 687 was available within the area code. The local
switch was configured to distinguish the absorbed ("predetermined")
digits from actual numbers by segregating them on separate levels.
Without knowing the specifics of that particular switch, I can't specify
the dialing plan, but it must have looked something like this:

1 = access for non-local numbers + vertical service codes
2XXX = local number, blank level, or nearby community
3XXX = local number, blank level, or nearby community
4XXX = local number, blank level, or nearby community
5XXX = local number, blank level, or nearby community
6 = absorbed by digit absorber
7 = absorbed by digit absorber
8 = absorbed by digit absorber
9XXX = local number, blank level, or nearby community
0 = operator (or access code)

The digit absorber in this case would have been type "AR" meaning
"absorb repeatedly." You could have dialed 6, 7, or 8 repeatedly, in
any order, with no affect. You could have dialed 687-0 and reached the
operator. Or 8888877776666786886786780. Did you ever try it?

As I've noted in previous posts here in T-D, similar situations existed
elsewhere. Example:

CARBONDALE, ILLINOIS, 1971 -- http://tinyurl.com/nd4m4
Like your hometown in New York, Carbondale was a simple situation -- it
avoided conflicts by segregating functions on separate levels:
- Levels 3, 7, and 9: local 5-digit numbers
- Levels 4 and 5: repeatedly-absorbed ("AR") digits.
- Levels 6 and 8: NNXs in nearby communities.
- Level 2: unused.

But the situation was more complicated in larger communities where it
was not possible to avoid conflicts by segregating functions on separate
levels. In such cases, a different type of digit absorber, type "A",
was used. The distinction:

A = The selector absorbs the specified digit once only; on
the next digit, it "trunks on all levels." This digit
must be dialed once (and only once) in order to reach
certain specified second digits. However, it is absorbed
(ignored) for any other second digit.

AR = The selector absorbs the specified digit repeatedly
unless a digit has been absorbed previously on a level
designated "A".

Two examples:

ANN ARBOR, MICHIGAN -- http://tinyurl.com/jtg3f
- Levels 2, 3, and 5: local 5-digit numbers.
- Level 6: repeatedly-absorbed ("AR") digit.
- Level 8: absorbed-once ("A") digit -- see note below.
- Level 4: NNXs to nearby communities.
- Levels 7 and 9: unused.

Note how the "A" digit 8 was used to resolve conflicts:
- 8 followed by 6, 7, 8, or 9 was a local 5-digit number.
- 8 followed by 1, 2, 3, 4, 5, or 0 was absorbed and ignored.

CENTERVILLE, IOWA, 1975 -- http://tinyurl.com/8axyn
- Level 6: absorbed-once ("A") digit -- see note below.
- Levels 5 and 8: repeatedly-absorbed ("AR") initial digits.
- Level 4: NNXs to nearby communities (plus one located in Centerville
itself).
- Levels 2, 3, 7 and 9: unused.

Note how the "A" digit 6 was used to resolve conflicts:
- 6 followed by 2,3,6,8, or 9 was a local 5-digit number.
- 6 followed by 5 was 658-XXXX in Cincinnati.
- 6 followed by 1,4,7, or 0 was absorbed and ignored.

So, you might ask, why didn't the telcos just segregate all Ann Arbor
and Centerville numbers on separate levels, like GTE did in Carbondale?

- Because every dialing plan has to avoid conflicts
between local 3-, 4-, or 5-digit numbers and NNX codes in
nearby communities reached by 7-digit dialing.

- Because every dialing plan has to consider how the
local dialing plans in nearby communities avoid
conflicts between *their* local (3-, 4-, or 5-digit) numbers
and the NNX codes used by *their* nearby communities.

- Because every NNX in an area code has to be unique.
A telco can't pick an NNX just because it's convenient
for the local dialing plan if it's already in use
somewhere else in the area code.

And ultimately, because all dialing plans within an area code form a
continuous web of inter-community 7-digit dialing, each one of which has
to avoid local conflicts.

Have you followed all this? Or are your eyes glazed over by now? If
you haven't followed it because it's too complicated, that's my point:
it is complicated! It's amazing that traffic engineers back in the 50s
and 60s were able to figure it all out.

Even more amazing is the fact that they were able to implement it with
electromechanical devices: Strowger switches, relays, and time-delay relays.

This technique is discussed in detail in "Notes on Distance Dialing,"
Section 4, "Typical Trunking Diagrams for Step-by-Step Offices,"
published by AT&T Engineering and Network Services Department, Systems
Planning Section, 1975. A PDF of Appendix A1 (the trunking diagram of a
hypothetical SxS switch) is posted at
http://tinyurl.com/29bgqm6

All this reminds me of a story. Back in the '50s when I was an
undergrad at U of M in Ann Arbor, I was living in a residence hall known
as East Quad. In those days, each residence hall had its own manual
PBX. All calls were dialed by the PBX operator to prevent any
unauthorized calls. Residents were not permitted to make inside calls.

I had a friend named John who lived in West Quad, which had incoming
number 2-4401. West Quad residents were not permitted to make inside
calls either.

John figured out that if he asked the operator for 8-2440, the operator
would dial it like any other 8-XXXX number. He'd then flash of the
switchhook on his room phone, effectively dialing 1. Thus, the central
office saw 82-4401, ignored the "A"-digit 8, and sent the call right
back to the West Quad PBX. John could make an inside call.

This technique worked well on busy evenings when student operators were
on duty. But John screwed up: he tried it on a weekday afternoon when
the Chief Operator was on duty. She recognized his voice, and politely
informed him the inside calls were not permitted. I've always wondered
if she figured out how he did it.

Neal McLain


HAncock4

unread,
Sep 18, 2011, 12:16:29 AM9/18/11
to
On Sep 16, 7:15 pm, t...@panix.com (Thor Lancelot Simon) wrote:

> Not such a major undertaking.  In roughly 1980 I lived in a rural area
> of New York State that still had 4 digit dialing.  Extension to a
> _longer_ number can be done automatically -- it is fully deterministic,
> you are just adding predetermined digits.

Vol 2 of the Bell Labs history (op cit) describes what had to be done,
and it was not trivial. As mentioned, they had to add digit-absorbing
selectors in step-by-step exchanges. While that's not replacing the
entire exchange, it's not something that simply gets plugged in
either.

Further, the new exchange designation has to be wired into other
exchanges, intermediate tandem switches, and other equipment so the
exchange can be reached.


> My number was 687-XXXX for external purposes, but for in-town callers,
> simply XXXX would do.  The "687", obviously, was just added onto the
> front when numbers went to 7 digits -- and there were towns near us
> with switches still configured to allow 3-digit dialing, which had had
> four digits prefixed to the front, too.

If someone's phone number was say 6235, how would the switch know if
someone was dialing 687-6235 or just 6235?

There were a lot of different dialing patterns and they all had to be
uniform so that someone in a town could dial 7 digits and the call
would still go through. If fewer digits would work--as it continued
to do so in many towns--so much the better, but making that happen
wasn't always that simple.

There was also the issue of dialing other towns nearby.

> However, there is no such mapping from longer numbers (8 digits) onto
> shorter numbers (7 digits).  Since New York City got only one area
> code in the original direct-dial plan, if there were really 8 digit
> numbers in circulation, some subscribers' numbers would have had to
> be completely changed, not just extended.  This is what I am a little
> skeptical about.

Many libraries offer the NYT on-line as well as microfilm. Check out
12/8/1946, pg 209, classified ad, Houses Queens, and you'll see an ad
by Listing Realty of Hillside Ave with HO 5-10412. You'll also see an
ad for BE 5-2874J.

For such eight digit subscribers, as well as party line subscribers
with a letter suffix, they all would need to get a new number when
their exchange went dial. In those years many people did get entirely
new numbers. There were Bell letters and booklets to customers and
special directories issued to reflect those changes.

Lots of people got new exchange designations.

Wes Leatherock

unread,
Sep 17, 2011, 8:18:47 PM9/17/11
to
--- On Sat, 9/17/11, Neal McLain <nmc...@annsgarden.com> wrote:

[ ... ]

> In the example you cite, the situation was straightforward:
> simply adding 687 worked because there were no local numbers
> beginning with 6, 7, or 8, and because 687 was available
> within the area code. The local switch was configured
> to distinguish the absorbed ("predetermined") digits from
> actual numbers by segregating them on separate levels.

[ ... ]

> A The selector absorbs the specified digit once only; on the next
> digit, it "trunks on all levels." This digit must be dialed
> once (and only once) in order to reach certain specified second
> digits. However, it is absorbed (ignored) for any other second
> digit.

[ ... ]

> AR The selector absorbs the specified digit repeatedly unless a
> digit has been absorbed previously on a level designated "A".

Digit aborbing had many uses in larger step-by-step areas, such
as Oklahoma City, Tulsa, Dallas, Fort Worth, Houston, San Antonio.

Certainly it would have been impossible to trunk large multi-exchange
cities like these without use of digit-absorbing.

I was on the receiving end of the woes that this could cause
when I got the number VIctor 3-6056 when I moved back to Oklahoma City
from Dallas many years ago.

The time number in Oklahoma City was REgent 6-0561. We got
calls all during the night every night from often-incoherent callers
with slurred speech who misidialed the first digit as 8 instead of 7.
A call starting with 83, because of the digit absorption from the
downtown office, absorped the digit 4.

The phone company soon changed my number when I complained. When
I was downtown, where my office was, I tried various combinations when
making calls to offices out of downtown and discovered many prefixes
where the secon digit could be ignored, since it would be absored,
just dialing six digits.

It varied depending on the origination and destination office,
since figuring out how to make thr tuning work in step-by-step office
varied according to the route. It must have been quite a challenge
for the traffic engineers, but they seemed to be quite comfortable
with it.

Wes Leatherock
wlea...@yahoo.com
wes...@aol.com

tlvp

unread,
Sep 17, 2011, 8:28:10 PM9/17/11
to
On Sat, 17 Sep 2011 10:14:40 -0500, Neal McLain wrote:

> ... [big snip] ...
> John figured out that if he asked the operator for 8-2440, the operator
> would dial it like any other 8-XXXX number. He'd then flash of the
> switchhook on his room phone, effectively dialing 1. Thus, the central
> office saw 82-4401, ignored the "A"-digit 8, and sent the call right
> back to the West Quad PBX. John could make an inside call.
>
> This technique worked well on busy evenings when student operators were
> on duty. But John screwed up: he tried it on a weekday afternoon when
> the Chief Operator was on duty. She recognized his voice, and politely
> informed him the inside calls were not permitted. I've always wondered
> if she figured out how he did it.
>
> Neal McLain

Hook-flash dialing was quite a trick to master, if you hadn't
quite ever needed to before.

A small performing group I was part of back in the late '60s
had been putting on an afternoon show for the inmates of the
Yale Psychiatric Institute (YPI), and when the show was over
we all retired to the ground floor bathrooms to change out of
costume and into civilian clothes. By the time we were in full
civvies again, 5 pm had come and gone, as had the receptionist,
and the entrance doors were all locked -- as was the dial on
the receptionist's pulse-dial (rotary) desk phone.

What to do? Dial 9 for an outside line, then the Yale campus
police number -- all by hook-switch flashing (!). Took about
half an hour to get all the timing right, but, yes, it *did*
ultimately all come together, and the campus cops came to
let us all out.

Cheers, -- tlvp
--
Avant de repondre, jeter la poubelle, SVP.

***** Moderator's Note *****

My dad taught me a different method. When he came across a phone that
had a dial-lock on it, he would hook-flash the operator (the trick,
btw, is to flash the hook at a consistent rate - most people try for
speed, which is the wrong way to go about it) and ask for assistance
in dialing, and he'd say the line kept going dead.

There was, however the one time on a frozen Saturday morning at a bar
in Boston where he was fixing a toilet, and needed to call the supply
house for a part that he needed, and he got impatient and took a pair
of pliers and bent the finger-stop up and out of the way of the
lock. When I got home from school on Monday, I asked him if anyone had
gotten mad, and he said "About what? We didn't do anything wrong"!

Some years later, we were in a basement in Boston, and I looked up and
say a lineman's handset hooked on a nail (the old, old kind, that you
had to dial with a pencil and that came in a real rubber housing),
with the leads still clipped across the protection block. It was, of
course, in "Monitor". I asked the guy who owned the house why it was
there, and he just shrugged his shoulder and said "Because the phone
man put it there". I told him it was hurting his phone line and that I
would remove it for him. My dad later told me, with a very big smile,
that it was the best tool in his box.

Bill Horne
Moderator

HAncock4

unread,
Sep 18, 2011, 6:09:56 PM9/18/11
to
On Sep 17, 8:18 pm, Wes Leatherock <wleat...@yahoo.com> wrote:

> The phone company soon changed my number when I complained. When I
> was downtown, where my office was, I tried various combinations when
> making calls to offices out of downtown and discovered many prefixes
> where the secon digit could be ignored, since it would be absored,
> just dialing six digits.

In the mid-1970s I worked for a business served by a small Centrex.
All extensions were in the 3xxx series, and we dialed 4 digits
internally. I was curious and dialed 417 and reached extension 3417.
So, actually only three digits were required in most cases. As an
aside, their switchboard was an old style cord board; I had assumed
Centrex switchboards would be modern cordless consoles.

Presumably the switch serving us was step-by-step, which ironically
was easily adapted to Centrex service. (Panel and No. 1 crossbar
could not support Centrex.) The irritating aural signals sounded like
step-by-step PBXs; Centrexes served by No. 5 Crossbar seemed to have
modern signals like a regular exchange. Also, toll calls were ONI,
that is, an operator had to come on to get the calling number, even
for suburban message unit calls.
On this switch when we transferred a call, we flashed the hookswitch
once, and the operator came on to do the transfer. On later Centrexes
(presumably served by ESS), a hookswitch flash would generate a
stutter dial tone and the person could dial the desired number
himself, or even easily set up a three-way call.


Side note: On the older Centrexes, when one dialed nine for an
outside line, there would be a slight pause and click before the
outside dial tone came on. But on the newer ones the dial tone
remained on continuously, no pause, no click.

Side note: On many PBXs and Centrexes there were tie lines to other
PBXs of the company. One would dial an access code (often 8 or 8n),
then the extension on the remote PBX. While usually one could not get
an outside line on the remote PBX, one could get a tie line, and dial
back to your own PBX, or another PBX if there were multiple tie
lines. Very large organizations had private networks interconnecting
numerous locations. In experimenting, I once ended up reaching
another company who shared our Centrex prefix--apparently the shared
circuitry at the central office did not have the necessary 'block' for
tie-line calls. Normally our extensions could not dial between two
separate companies. (The business I reached was an entirely separate
organization).


Although the Bell System prided itself on standardization, it appears
PBX, Centrex, and tie line arrangements of large organizations varied
considerably from one instalaltion to another, and probably there was
variation in local practices, too. Many dial PBX's started their
extension numbering with 2, but others did have a 1 series. Dial
codes and procedures for tie line arrangements varied greatly.


In the 1950s and 1960s, the Bell System developed a variety of
relatively small modern dial PBXs that had cordless consoles, a
compact switch, and more automated features (eg 'camp on'). Vol 2 of
the Bell Labs history gives some description of those, though mostly
the internals of the switch. Unfortunately, there is no mention of
prices. I would love to see a Bell System commercial price list from
say 1965 listing the rentals of their various dial and manual PBXs and
corded and cordless switchboards. Particularly, for a small _dial_
PBX, I wonder about the relative cost of a cordless vs. corded
switchboard. since a cordless board required considerably more
circuitry but didn't yield much more productivity to the customer.

Neal McLain

unread,
Sep 18, 2011, 10:58:23 PM9/18/11
to
HAncock4 <withh...@invalid.telecom-digest.org> wrote:

> On Sep 16, 7:15 pm, t...@panix.com (Thor Lancelot Simon)
> wrote:

>> Not such a major undertaking. In roughly 1980 I lived in a
>> rural area of New York State that still had 4 digit dialing.
>> Extension to a _longer_ number can be done automatically --
>> it is fully deterministic, you are just adding predetermined
>> digits.

>> My number was 687-XXXX for external purposes, but for in-town
>> callers, simply XXXX would do. The "687", obviously, was
>> just added onto the front when numbers went to 7 digits --
>> and there were towns near us with switches still configured
>> to allow 3-digit dialing, which had had four digits prefixed
>> to the front, too.

> If someone's phone number was say 6235, how would the switch
> know if someone was dialing 687-6235 or just 6235?

Most probable answer: there were no numbers in the form 6XXX, 7XXX, or
8XXX. As I explained in my post of Sep 17, 10:14, the dialing plan
segregated local 4-digit numbers from the absorbed digits 6, 7, and 8.
Thus:

1 = access for non-local numbers + vertical service codes
2XXX = local number, blank level, or nearby community
3XXX = local number, blank level, or nearby community
4XXX = local number, blank level, or nearby community
5XXX = local number, blank level, or nearby community
6 = absorbed at the first selector by "AR" digit absorber
7 = absorbed at the first selector by "AR" digit absorber
8 = absorbed at the first selector by "AR" digit absorber
9XXX = local number, blank level, or nearby community
0 = operator (or access code)

But, as I noted previously, the above dialing plan is just a best-guess
on my part. I assume Thor will let us know which levels actually were
used for local numbers.

As for Thor's original statement, "Not such a major undertaking," it
would been a fairly straightforward undertaking at the local exchange
level. Each first selector would have to have been equipped for
digit-absorbing circuitry, and strapped to absorb the specific digits
relevant to the exchange (6, 7, and 8 in this case).

The *really* major undertaking would have been at the area-code level,
where the job was to assign each community within the area code one or
more NNX exchange codes which:

- Wouldn't conflict with the local dialing plan.

- Wouldn't conflict with the local dialing plan of any neighboring
community reached by seven-digit dialing.

- Wouldn't conflict with any existing NNX codes within the area code.

- Were true NNX codes (which excludes N0X and N1X codes, which didn't
exist until the '70s, and even then were restricted to larger cities
already using seven-digit dialing plans).

In a later message in this tread, tlvp <mPiOsUcB.EtLlL...@att.net> wrote:

> On Sat, 17 Sep 2011 10:14:40 -0500, Neal McLain wrote:
> ... [big snip] ...
>> John figured out that if he asked the operator for 8-2440,
>> the operator would dial it like any other 8-XXXX number.
>> He'd then flash of the switchhook on his room phone,
>> effectively dialing 1. Thus, the central office saw 82-4401,
>> ignored the "A"-digit 8, and sent the call right back to the
>> West Quad PBX. John could make an inside call.

> Hook-flash dialing was quite a trick to master, if you hadn't
> quite ever needed to before.

Well, yeah, but if you're only dialing a 1, it's pretty easy! The trick
is to do it fast enough that the CO won't hang up, and that it won't
attract the attention of the PBX operator.

Neal McLain




Wes Leatherock

unread,
Sep 19, 2011, 7:46:05 PM9/19/11
to

--- On Sun, 9/18/11, Neal McLain <nmc...@annsgarden.com> wrote:

>
> The *really* major undertaking would have been at the
> area-code level, where the job was to assign each community
> within the area code one or more NNX exchange codes which:
>
> - Wouldn't conflict with the local dialing plan.
>
> - Wouldn't conflict with the local dialing plan of any
> neighboring community reached by seven-digit dialing.
>
> - Wouldn't conflict with any existing NNX codes within the
> area code.
>
> - Were true NNX codes (which excludes N0X and N1X codes,
> which didn't exist until the '70s, and even then were
> restricted to larger cities already using seven-digit
> dialing plans).

A list of prefixes was assigned for each area code, and all of
those considerations were taken into account when the list was first
set up. Prefixes were not just assigned randomly. In locations which
already had multiple prefixes, those were incorporated into the first
area code-wide assignment.

There were also some locations where a community of interest
existed between offices in different area codes, where the prefix had
to be "protected" in both area codes.

A prime example was the greater Kansas City Metropolitan exchange,
since the metro area extended across two states with seven-digit
dialing. The Missouri side had area code 816, the Kansas side 918.

Of course, this consideration ceased to be a factor when mandatory
10-digit (or 11-digit) dialing on local calls came into existence.

Wes Leatherock
wlea...@yahoo.com
wes...@aol.com




tlvp

unread,
Sep 20, 2011, 12:50:36 AM9/20/11
to
On Sat, 17 Sep 2011 20:28:10 -0400, after tlvp wrote

> ...
> Hook-flash dialing was quite a trick to master, if you hadn't
> quite ever needed to before. ...
>

Moderator added:

> My dad taught me a different method. When he came across a phone that
> had a dial-lock on it, he would hook-flash the operator (the trick,
> btw, is to flash the hook at a consistent rate - most people try for
> speed, which is the wrong way to go about it) and ask for assistance
> in dialing, and he'd say the line kept going dead. ...

1) Hook-flashing a Yale Operator on a YPI phone wouldn't go very well,
as the Yale operator would simply respond as if we were YPI inmates
having somehow gotten unauthorized after-hours access to the phone.
Campus Police perhaps likewise, but they'd come to make sure we were
properly confined again, and then learn we weren't inmates at all :-) .

2) A consistent rate is important, of course, but the speed is, too:
slower than about 5 pulses per second and your click-stream becomes
not a pulse-dial 9, for example, but rather nine pulse-dial 1s.

The trick to getting a consistent *and* fast stream of clicks, I found,
was (i) to alternate fingers on both hands, (ii) to hook-flash in
perceptible, systematic patterns, e.g., three quick triplets for a 9,
Click-click-click Click-click-click Click-click-click, with other
suitable patterns for other digits, and (iii) to aim for something
like 6 flashes per second (360 as a metronome setting) or more.
HTH :-) .

3) Q.: Will hook-flash dialing still work on today's DTMF-based PBXes?

Neal McLain

unread,
Sep 20, 2011, 12:14:56 AM9/20/11
to
On Mon, 19 Sep 2011 16:46:05 -0700 (PDT), Wes Leatherock
<wleat...@yahoo.com>> wrote:

> There were also some locations where a community of interest
> existed between offices in different area codes, where the
> prefix had to be "protected" in both area codes.

> A prime example was the greater Kansas City Metropolitan
> exchange, since the metro area extended across two states with
> seven-digit dialing. The Missouri side had area code 816, the
> Kansas side 918.

You mean 913.

> Of course, this consideration ceased to be a factor when
> mandatory 10-digit (or 11-digit) dialing on local calls came
> into existence.

Don't those two cities have independent 7-digit dialing plans now? I
thought 816 and 913 each had 7-digit dialing internally but 11-digit
dialing across the river

Another example: DC/Maryland/Virginia metro area. Before 1953, the
entire area had a single 6-digit dialing plan (2L+4D). In '53, 7-digit
dialing was introduced (2L+5D). Sometime later, the dialing plan was
split by area code, with 10-digit dialing across boundaries. Since
then, both Maryland and Virginia have gotten overlays, so the metro area
now has five area codes with 10-digit dialing in Maryland (240+301) and
Virginia (671+703). DC (202 still has 7-digit dialing.

I suppose someday 202 will need relief, with the obvious choice being an
overlay. However, somebody here on T-D once suggested a split of sorts:
put the federal government in its own area code -- 666.

Neal McLain



Neal McLain

unread,
Sep 20, 2011, 6:28:23 PM9/20/11
to
On Sep 19, 11:14 pm, Neal McLain <nmcl...@annsgarden.com> wrote:

> Another example: DC/Maryland/Virginia metro area. Before 1953, the
> entire area had a single 6-digit dialing plan (2L+4D). In '53, 7-digit
> dialing was introduced (2L+5D). Sometime later, the dialing plan was
> split by area code, with 10-digit dialing across boundaries. Since
> then, both Maryland and Virginia have gotten overlays, so the metro area
> now has five area codes with 10-digit dialing in Maryland (240+301) and
> Virginia (671+703). DC (202 still has 7-digit dialing.
>
> I suppose someday 202 will need relief, with the obvious choice being an
> overlay. However, somebody here on T-D once suggested a split of sorts:
> put the federal government in its own area code -- 666.
>
> Neal McLain

Oops ... I mean 571, not 671.

Neal

HAncock4

unread,
Sep 20, 2011, 11:12:20 PM9/20/11
to
On Sep 20, 12:14 am, Neal McLain <nmcl...@annsgarden.com> wrote:

> I suppose someday 202 will need relief, with the obvious choice being an
> overlay.  However, somebody here on T-D once suggested a split of sorts:
> put the federal government in its own area code -- 666.

Speaking of Washington . . .

Washington went dial around 1930. Washington grew somewhat during the
New Deal as the alphabet soup agencies were formed, but then grew
tremendously during WW II. (The Pentagon alone had about a 16,000
station PBX. See David Brinkley's excellent "Washington Goes to
War".)

Would anyone know what kind of switch type was used for Washington
dial service, especially as the city grew? Also, did Washington get
any special long distance switches or trunks to meet wartime demand?
Did the military have an early version of Autovon during WW II to
interconnect Washington with military bases around the country? I
recall reading that they did build a new cross country toll line just
before the war, but I can't recall the details. The No. 4 toll
crossbar switch first went into service during WW II, but it was based
in Philadelphia, not Washington. Also, to meet war time traffic
needs, they narrowed the bandwidth on toll lines to squeeze in more
capacity.

With the press of wartime traffic, long distance facilities to/from
Washington must have been strained. I wonder what percentage of toll
calls were completed on a demand basis vs. a delayed basis, and if
operators had a priority system for handling calls.

(There's a Bell Labs volume on military service, but it's mostly about
fire control, radar, and military radio communications.)

Pawlowski, Adam

unread,
Sep 21, 2011, 9:35:03 AM9/21/11
to
Date: Tue, 20 Sep 2011 00:50:36 -0400
From: tlvp <mPiOsUcB...@att.net>
To: reda...@invalid.telecom-digest.org.
Subject: Re: EXchanges (was: area code named beer)
Message-ID: <mi89yjrouoys$.16iyqtm3qt1o4$.d...@40tude.net>

On Sat, 17 Sep 2011 20:28:10 -0400, after tlvp wrote

> ...
> Hook-flash dialing was quite a trick to master, if you hadn't quite
> ever needed to before. ...
>

It has come in handy a few times where you need to dial and the "dial"
function of whatever is handy doesn't work.

3) Q.: Will hook-flash dialing still work on today's DTMF-based PBXes?

It does not work with any VoIP "gateway" product I've come across, I can tell
you this. We don't presently deploy these devices anywhere, but, in my own
limited testing, "pulse" dialing doesn't work. If anything, it causes the port
to reset as though you have hung up the phone. If there is an "adapter" made
for such a legacy device, readily available, I don't know.

This had at least stopped my from a novelty project of putting a rotary 1A2
set on our VoIP system here, but, if it were deployed as a "Solution" to
replacing phones in a business type environs, I can see calls coming in from
people who flipped the T/P switch and now cannot dial. I haven't tried on
some of the older equipment like the Merlin Legend , which I should .

Mark J. Cuccia

unread,
Sep 21, 2011, 6:33:52 PM9/21/11
to

Neal McLain wrote:

> Wes Leatherock wrote:

>> A prime example was the greater Kansas City Metropolitan exchange,
>> since the metro area extended across two states with seven-digit
>> dialing. The Missouri side had area code 816, the Kansas side 913.

[NOTE that I have corrected an error, in the above quoted paragraph]

>> Of course, this consideration ceased to be a factor when
>> mandatory 10-digit (or 11-digit) dialing on local calls came
>> into existence.

> Don't those two cities have independent 7-digit dialing plans now?
> I thought 816 and 913 each had 7-digit dialing internally but
> 11-digit dialing across the river?

Yes, in the Kansas City MO/KS metro area, local/EAS calls _within_
one's _own_ state/NPA are still dialable as just seven-digits,
although ten-digits (and 1+ten-digits) are permissive for such
intra-state/NPA local/EAS calls,

but local/EAS calls that _cross_ the state/NPA boundary are now
mandatory ten-digits (permissively 1+ten-digits).

The 816/MO side is eventually going to be overlaid with 975. This was
announced by SW-Bell and NeuStar-NANPA ten years ago, back in 2001,
but it has been "on hold" ever since. Whenever that 816/975 overlay
does take effect, then ten-digits mandatory will also take effect for
local/EAS calls within the 816/MO-side. I don't know if at&t/SW-Bell
and the rest of the telco industry, along with Kansas regulatory and
NANPA, will work to make local/EAS calls within the 913/KS-side also
as mandatory ten-digits for "consistency" purposes, nor not. Of
course, whenever the 913/KS-side ever does need relief which is also
most likely going to be an overlay, then ten-digits will become
mandatory for intra-913/KS local/EAS calls as well, if not already so
by then. BTW, 552 is the likely relief code for 913/KS.


**** MAYBE NOT 552! 552 is now a future 5xx PCS code! Also, 913/KS
is NOT expected to exhaust for QUITE some time now (as of 2011) ****


When the Ottawa-ON / Hull-QC metro area needed to eliminate protected
c.o.codes/7-digit local/EAS dialling to delay area code relief by
"squeezing" as much remaining life as possible from 613/ON and 819/QC,
Bell Canada, the CRTC, the CNA, etc. actually made local/EAS dialling
as mandatory ten-digits _throughout the entire_ 613/ON-side _and_
819/QC-side, even for intra-province/NPA local/EAS calls _everywhere_
in those NPAs, even in places outside of the Ottawa-ON / Hull-QC metro
area. Subsequently, the (entire) 613/ON-side has been overlaid with
343 (in 2010). The (entire) 819/QC-side will be overlaid with 873
next year (in 2012).

> Another example: DC/Maryland/Virginia metro area. Before 1953, the
> entire area had a single 6-digit dialing plan (2L+4D). In '53,
> 7-digit dialing was introduced (2L+5D).

Note that the numbering/dialing of Washington DC Metro (including the
VA and MD suburbs) converting from 2L-4N to 2L-5N was a "staged"
process. There were two or three staggered cutovers affecting specific
exchanges/central offices in various neighberhoods of the metro area
in the late 1940s/early 1950s-era. Other cities which changed from
2L-4N to 2L-5N did it as a single city/metro-wide cutover, where
_everything_ in the entire metro area that was 2L-4N changed to 2L-5N
all at one time, overnight (literally). But not the Washington DC
metro area, nor various other (multi-switch) cities. However, any/all
cutovers in the old electromechanical (SXS, Panel, Crossbar, etc) era
that involved numbering/dialing did NOT have a permissive period, but
such numbering/dialing cutovers were "flash-cut" (or nearly so, i.e.
there might have been an inadvertent permissive dial period for a few
hours or even a few days, as telco had to individually "turn-on" the
new numbering/dialing, and then "turn-off" the old/obsolete numbering/
dialing).

> Sometime later, the dialing plan was split by area code, with
> 10-digit dialing across boundaries.

It was in October 1990, when the correct destination area code was
now _required_ for ten-digit (permissively 1+ten-digit) local/EAS
dialing which crossed the state/district/NPA boundaries between
DC/VA/MD. Permissive ten-digit local/EAS dialing (also permissive as
1+ten-digits) had been in place by BA/C&P for some time prior to
October 1990, though.

> Since then, both Maryland and Virginia have gotten overlays, so the
> metro area now has five area codes with 10-digit dialing in Maryland
> (301 and 240) and Virginia (703 and 571). DC (202 still has 7-digit
> dialing.

[NOTE that I have slightly edited, and corrected an error, in the
above quoted paragraph]

BTW, probably sometime next year, the eastern Maryland (Baltimore,
Annapolis, etc. area), with 410-overlaid-with-443 (since 1997; also
the 301/410 split was in 1991), will get an additional overlay with
667. NeuStar-NANPA/etc. announced this additional overlay in 2001,
but it has never been actually implemented. Also in 2001, the
additional 227 overlay to 301-and-240 for western Maryland (DC metro
as well as points further west, bordering West Virginia, (WV, BTW
since 2009, has been 304-overlaid-with-681), but there have never
been any formal implementation dates announced for this additional
Maryland 301/240/227 overlay. Of course, ten-digit dialing within the
state is mandatory for all local/EAS calling (1+ten-digits permissive
for local/EAS), so the groundwork is already in place.

> I suppose someday 202 will need relief, with the obvious choice
> being an overlay.

Some time back, it was thought that either 746 or 821 could have been
the relief area codes for future 202/DC relief. But neither will be
the case, since 202-746 and 202-821 are already now assigned as "POTS"
202-NXX c.o.codes in DC.

It seems that the future relief code for 202/DC might now be 771.
381 seems to be the future relief code for 703/571 in northern VA.

> However, somebody here on T-D once suggested a split of sorts:
> put the federal government in its own area code -- 666.

All kidding aside, 666 can NOT be a geographic NPA code. Remember that
NPAs with an identical digit in the second (B) and third (C) position
are RESERVED (or eventually assigned) for "special" functions. These
are SACs, the original definition (which I prefer) was "Special Area
Code", but the 1980s/forward definition is "Service Access Code".

800, 888, 877, 866, 855, etc. Toll-Free,
500, 533, 544, 566, etc. once for Personal Numbering
(but now the 5YY SACs are used for some indeterminable function!),
900, future 922, etc. PAY-PAY-PAY per-call,
700 LD-Carrier services,
and the 6YY range (600, 622, etc.)
all fit this criteria.

The entire 6YY range, including 666, with 600 being the only assigned
such SAC "in service" at present (since 610 was swapped for 600 in
1993), is reserved for Canada for their own special services.


ALSO, HAncock4 wrote:

> Speaking of Washington,
>
> Washington went dial around 1930. Washington grew somewhat during
> the New Deal as the alphabet soup agencies were formed, but then
> grew tremendously during WW II. (The Pentagon alone had about a
> 16,000 station PBX. See David Brinkley's excellent "Washington
> Goes to War".)
>
> Would anyone know what kind of switch type was used for Washington
> dial service, especially as the city grew?

Washington DC (eventually including the Maryland suburbs, but I don't
know about the northern Virginia suburbs) was one of the twenty-some
metro areas in the US, most of them being BIG urban metro areas, which
went dial in the 1920s/30s with Panel switching, latter supplemented
with #1XB, i.e., "Revertive Pulsing". There were no other areas in
the US that had such Panel/#1XB (RP) switching, and NONE in Canada
(except for the experimental "Lorimer" RP systems that didn't last
long, in the EARLIEST part of the 20th Century, in a few places in
Canada).

During the 1950s, #5XB (which was brand new as of 1948) began to be
added to both Panel/#1XB cities, as well as SXS cities, throughout
all of the US and Canada. #5XB was also used for manual-to-dial
conversions, as well as continued brand new installations of SXS for
manual-to-dial conversions, well into the 1960s-era.

Mark J. Cuccia
markjcuccia at yahoo dot com

HAncock4

unread,
Sep 16, 2011, 9:57:33 PM9/16/11
to
On Sep 16, 10:24�am, HAncock4 <withh...@invalid.telecom-digest.org>
wrote:

> DDD required that all subscribers have a uniform ten digit number--


> three digit area code and seven digit local number. �In 1950 a great
> many subscribers in smaller towns and cities had phone numers with
> three, four, five, or six digits, and all had to be converted to seven
> digits. �This was a major undertaking that took years to complete.

P.S. Many times the "conversion" was accomplished at the same time a

Reply all
Reply to author
Forward
0 new messages