[GreenKeys] TWX Services

[magwheels54 at yahoo.com]

Hi Jim
Thanks for the extensive write up. Sounds like they didn’t know what method to use to gang all these machines together with the technology they had at the time. You’re right, I’m sure customer billing by the phone company played a big role in driving what was adopted.
I guess I thought, by 1949 they would’ve used a phone to dial another user. But I guess, if people were just sending a text message to each other, without a computer, manual switchboard was the only way to connect two teletype users. 
I read about the subscription sets they had to connect two machines with the same customer. Like if they had one machine at their factory and another one at their warehouse across town. The subscription sets would directly connect both those machines together over the TWX line but to no one else.
I still somehow believe that the Dataphone or call control approach could be used as an alternative to the internet. But with voice and data lines so intertwined now on an IP network, it may not matter. 
I guess keeping my model 19 hooked up to internet on line 1 and my radios on line 2, will be it for now. 
Andy 

Sent from Yahoo Mail for iPhone


On Tuesday, April 18, 2023, 10:46 AM, Jim Haynes <jhhaynes at earthlink.net> wrote:

TWX used manual switchboards until about 1959 when Dial TWX went into
operation.  Telex in Europe (and introduced into the U.S. by Western
Union) was dial up.  My belief is that this had to do with customer
expectations for billing.  In the U.S. long distance phone calls and
TWX calls generated bills showing the date and time of day, the number
called, the location of that number, and the duration of the call and
how much was charged for it.  Switchboard operators used the Calculagraph
clock to measure the time duration of calls.  This was printed on toll
tickets, which then were manually processed by the people who handled
billing.

Telex in Europe and perhaps long distance telephony there too used a
simpler method.  When a call was connected a counter associated with the
caller's line was connected to a pulse generator.  The pulse rate
depended somewhat on the distance called.  The customer bill showed
just the number of pulses that had been accumulated during the billing
period.  This was all easily done by standard telephone switching
equipment.

The Bell System started what was once called fully automatic customer
dialing about 1949.  Where it was available the caller could dial his
own long distance calls.  Equipment would record the calling and called
numbers and the starting and stopping time of the calls on punched paper
tape.  Then a data processing machine built of relays could read the
tapes and sort the data into individual call records that could be handled
just like switchboard operators' toll tickets.  It took until about 1959
for the entire Bell System and the independent companies to get 
substantially all customer telephones' toll charging working this way.

Now manual TWX had used a variety of transmission mechanisms.  Narrow
bandwidth telegraph circuits in places, voice frequecy carrier channels
over voice-grade circuits, concentrators that shared a number of
circuits among a larger number of customers.  With customer dialing
of toll calls in place the company decided the voice switched network
could also be used for TWX and other switched data services.  And
customers were also doing it themselves by using acoustic-coupler
modems with voice telephones.

TWX remained a data-only service, but TWX machines had to have an earphone
or a speaker so the callers could hear dial tone and other tones and voice
announcements.  DataPhone had the assumption that callers and callees
would converse by voice before switching to data transmission, so its
terminals included telephones.  Other services were proposed but not
implemented.

In that connection, the low-speed TWX and DataPhone modems were full
duplex and FSK. So there were two different frequency pairs that could
be chosen for the calling station to transmit on.  And for each of those
there was an option whether the higher or lower tone would be mark or
space.  Thus by strapping options in the modem there were eight different
mutually incompatible combinations that could be used for different 
services and charged for at different rates, should the company and the
FCC agree that they were needed..

     ---

     "Ya can argue all ya wanna, but it's dif'rent than it was."
     "No it ain't! No it ain't!  But ya gotta know the territory."
         Meredith Willson, The Music Man



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