This rather colourful map was produced by the Post Office In 1937 to celebrate 10 years of international radio telephone.
At that time the technology had spread rapidly from the original London to New York circuit and by 1939 it was possible to interconnect 93% of the world’s telephones.
In terms of traffic and coverage HF telecommunications reached its peak in the 1950’s remaining fairly static until around 1970 gradually being superceded by cable and satellite. But of course the technology continued to improve.
I would just like you to hear a few short examples of what HF telecoms circuits sounded like.
The London recording is in fact a double hop circuit received at Baldock receiving station echoed back from Amman.