[kylegordon]

UK analogue strowger exchanges did not permit the called party to clear down the line - that was the job of the calling party. A legacy function of being 'patched through'.

"Called Subscriber Held", a feature that was carried into early digital exchanges because people expected it to work in the manner you describe, even though afaik it was designed for the other purpose of keeping the line open whilst operators patched it through, trunk lines picked up the tone, etc.

My grandpa was a something like chief engineer for the West Coast of Scotland phone network. I have so many questions I wish I could ask him these days.