Jacks, Plugs Wall Outlets ...timeline

[oldguy]

I'm 69 & as a kid & an adult, all our phone in California (Cupertino area) our phones were hard wired until modular phones came out.

[Haf]

USA

389 A jack and 273 A plug

Here is an example of an 1930's 389 A and 273 A  three contacts jack and plug, metal housing with indentations on the plug. Imagine the modern gray cord to be a cloth covered three conductor cord going to a 534 A sidetone subset .
I just missed another of those plugs due to the stupid ebay restrictions for outside US bidders, even with an US shipping address.
The original picture taken from the 1934 BLR mentioned earlier here. Thank your for contributing to the TCI Library, Chuck Hensley.

Haf

[Pourme]

Interesting, resembles the 1/4" jack we uses to have on headphones in the US.