[GreenKeys] TWX-TELEX history

[Henning Treumann]

2015-12-29 18:30 GMT+01:00 Jeffrey D Angus <jdangus at att.net>:

> Indeed an interesting read, thank you Henning.
>
> Looks like the big difference between switch telephone and switched
> teleprinter equipment was the end-to-end continuous copper
> connection. Excluding the use of tape equipment in the central office.
>
> Towards the last periods of operation of the Telexs and TWX networks,
> didn't they switch over to modems, so they could send the data over
> traditional voice circuits?
>

yes, there were different VF systems in use. Some countries uses a V.21
derivate
and others like Germany a Siemens system called ED1000.
Main difference are the used tones.
But also these systems were connected to separate Telex central offices.
The current line was just replaced by a VF system.
Modern electronical machines like Siemens T1000 had a build in modem
for that and older mechanical machines like T100 were connected with a
separate modem as line termination.

Henning
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