[GreenKeys] Networking of Dial TWX

Fri Jan 26 01:06:31 EST 2007

Regarding the networking of TWX...

In the Chicago area all 4 row TWX was in the 910 numbering plan and  
all the machines in the Chicago and suburban areas had private line  
voice band channels to the Congress central office.  While the  
technology for switching was the same as the voice network it is  
important to remember that it was SEPARATE from the DDD network.  3  
row dial TWX was another story.  On August 31, 1962 all of the  
Teletype operators operated a cut-over key to connect to the regular  
DDD network.  The 101A and 101B datasets (modems) were pre-installed  
for this purpose.  Each machine had a listen only handset for call  
progress. These machines included 15s 19s and 28s.  Model 26 machines  
were all removed by this time.  They were only used in the Manual TWX  
service.  Manual TWX was nation-wide by 1935 and expanded to hundreds  
of locations across the country, all handled by operators with manual  
cord boards and Model 14 strip printers.

After the 4 row ASCII machines (with 101C datasets) were deployed if  
a subscriber dialed from a 3 row machine on the DDD network into the  
4 row TWX network they were connected to a set of 5 to 8 level  
convertors, also located at major TWX switching centers.  At  
Christmas time many customers wanted us to send them Baudot art for  
the holidays.  This was a real terrible time at the convertor site  
with the convertors filling up for hours at a time, driving the  
foreman and his craftsmen nuts!  The General Telephone System also  
partnered with the Bell System for TWX service.  Smaller independent  
companies provided the wire and we Bell people installed and  
maintained the machines.

There is a very interesting Bell System Practice (BSP), the 972 layer  
if memory serves, that explains the TWX and WADS networks.  There is  
a copy at our museum but I no longer have one here.  It has a map of  
the US and Canada and the points of switching.

At some point after the sale of TWX to WUTco the networking was  
modified to suit their needs.  Also connecting 3 row machines to the  
DDD network was no longer possible due to regulatory requirements.   
We did hook up Model 33s to the DDD network and used them for  
computer terminals as you know but that is a whole different story.   
We had one machine in a Barrington High School classroom that had to  
be replaced before the beginning of each school year due to the hard  
use the students gave the machines.

A professor in Louisiana specializes in the history of telephone and  
teletypewriter switching and trunking.  I have not heard from him in  
some time, his name is Mark Cucia.  He has many facts that are  
interesting.  Two things I remember are... 1947 the year the Bell  
System launched the Direct Distance Dialing network.  199? the year  
the last manual office in the USA was converted to dial in a rural  
Nevada town.

Don
K9TTY
Illinois Bell Telephone 1966-1992
Ameritech Network Services 1992-1996

On 25 Jan 2007, at 10:48 PM, Don Robert House wrote:

Teletype is a contraction of Telephone Typewriter.

TWX is a contraction of Teletypewriter Exchange service.
TELEX has more letters but means the same thing.

When we sold TWX to Western Union they changed the name of both  
services to:
TELEX I  for TELEX
TELEX II for TWX

In house we also used a couple of other terms such as DTWX which  
simply added Dial to Teletypewriter Exchange service.
Then there was a special call control unit that had small lamps to  
monitor the call progress.  It was only experimental and never got  
implemented
Called WADS D  Wide Area Data Service - Dial

Don

Ye olde Teletype repairman

On 25 Jan 2007, at 12:16 AM, Richard Dillman wrote:

I have a question.  But first a story.

Back in the early eighties in installed a teletype link between my  
house and my girlfriend's house.  Those were the days when you could  
call up the telephone company and order a 50 baud line between any  
two points.  When the installers showed up at my place they were  
confused.  "We hate to bother you, we must have the wrong address.   
The order says we're supposed to terminate a teletype line here but  
it's a residence, not a business."  I ushered them in and explained  
the situation.  "Ah!", they saud.  "We will make sure it's an extra  
clean line!"  So Donna and I had our nice little link, complete with  
auto start, well before email was a gleam in the general public's eye.

We went our different ways but always kept in touch.  Tonight she  
sent me an email about the TWX machine she had at an airline she  
worked for.  She asked what the derivation of the term TWX (or telex,  
for that matter) is.  I didn't know the answer.  I'm sure someone  
here does.

RD

=================================
Richard Dillman, W6AWO
Maritime Radio Historical Society
http://www.radiomarine.org
Collector of Harleys, Willys and
Radios over 100lbs.
=================================
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