[old-ager]

> the old suckers still were operational

They don't contain any semiconductors. Only wire, insulation, plastic or a pre-plastic material, paper, glue, cloth and metal.

[riverdawg]

"... pre-plastic material"

Probably Bakelite, which was commonly used for telephone housings before 1950 or so. I think it is considered an early type of plastic, although it is harder than modern plastics. I have a restored Art-Deco style Bakelite phone from the 1930's with no rotary dial; so the phone will ring and receive incoming calls but you can't use it to dial out. (I'm thinking about putting it in our daughter's room!)