[GreenKeys] Telex Circuit Needed

[wa3frp at aol.com]

Here are a few comments from someone who was involved in Telex and TWX in the USA. 
 
Henning is correct in saying that the Western Union Telegraph Telex network used Siemens TW-39 signaling.  The other Siemens Telex exchanges were TWM-2 for large cities withTW-56 and TWK-4 for small cities. All exchanges used the same loop signaling. Two different configurations were offered The first option, sometimes called local or loop service, provided a 60 milliampere loop circuit from the exchange to the customer teleprinter. The second option, sometimes called long distance or polar was used when a 60 milliampere connection could not be achieved due to the high resistance of a physically long loop. This configuration provided a ground return polar circuit using 35 milliamperes on separate send and receive wires. By the 1970s, and under pressure from the Bell operating companies wanting to modernize their cable plant and lower the adjacent circuit noise that these Telex circuits sometimes caused, Western Union migrated customers to a third option called F1F2. This F1F2 option replaced the DC voltage of the local and long distance options with modems at the exchange and subscriber ends of the Telex circuit.
 
To my knowledge, neither Telex nor TWX is offered commercially in the USA.  In the last days of Telex and Telex II, which TWX was named after the Western Union acquisition in the late 1970s, Western Union offered a new service called EasyLink.  EasyLink was sold to AT&T when Western Union exited the common carrier business. 

73 Russ WA3FRP