Data communications over telegraph circuits 1948

That was all pretty much worked out by the mid-1930's or so! Some of the test equipment developed post-war was certainly better due to technologies that improved during the war years though (better vacuum tubes primarily).

But even the basis for today's digital network, Pulse Code Modulation, had been worked out to at least some degree pre-war.

Of course the big thing in that respect was that nobody had a handle on just which infrastructure was the most useful, until Claude Shannon published his work in the late 1940's. "A Mathematical Theory of Communications" set the direction toward an all digital Public Switched Telephone Network (PSTN), but of course it couldn't actually be accomplished until all digital common control switching systems could be designed too, and that require transistors (and general purpose computers).

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Heh... the "final mile" is almost identical today with what it was in maybe 1920! "Very tough" is a very accurate description! (So far they've managed to take the loading coils out and use 26 gauge wire with plastic insulation instead of 24 gauge with paper insulation.)

However, the changes that made "switched message traffic" so cheap compared to telegrams, pretty much did come from WWII technology: better vacuum tubes, mostly developed for RADAR.

The "planar" microwave triode type WE416 made the TD-2 microwave system possible. This tube had parallel elements, with a cathode oxide coating 0.0005" thick and cathode-grid spacing of 0.0006"! The grid was made of wires 0.0003" in diameter and was mesh of wires spaced 1000 per inch. The grid-plate spacing was 0.012".

Those tubes were used in both the transmit and the receive sections of the TD-2 systems that were installed across the country in the late 1940's and early 1950's. That spelled the end of needing to holler into the telephone on cross country calls in order to be heard (as can be seen in movies from 1930's and 1940's).

That, with a boost from the crossbar switch, made the telegram a thing of the past, even by the mid-1950's, and Direct Distance Dialing in the 1960's merely put a headstone on the grave. (And the all digital network hid the grave in the brush and grbutt where nobody even notices it anymore.)

Telex and TWX services however were still viable until the FAX machine took off, along with computer modems, in the 1980s.

But, an interesting thing happened with what was left of WUTCO's Telex... which was the right of way for their telegraph lines. That came to be owned by a company named TRT Telecommunications Corporation. It was owned for a time by Pacific Corp's telecom arm, Pacific Telecom Inc (PTI), all based in Vancouver WN and Portland OR.

I won't name names... but at one point, somewhere about 1992 there was an move that had the head of TRT succeeding the head of PTI. However, it was a disaster, and in the process of divesting themselves of the individual they also divested themselves of TRT. Which was *big* mistake. Those rights of way turned out to be worth *several* times was they sold the company for!

Essentially that was the end of what had remained of WUTCO's Telex network, and it also turned out to be the beginning of the end for PTI too (that wasn't the only basic mistake they made about that time).

WU was into telecommunications, with at least private line carrier and satellite systems, competing with AT&T for a time in the early 1980's. They didn't do well...

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