I have argued elsewhere and at length that what matters isn't the telephone per se but the Public Switched Telephone Network, which I claim is the Second Network (the First being the Universal Postal Union which enables you to send physical mail to arbitrary people in the world, and the Third being the Internet)
The thing these have in common is that they're connecting all the people. There is no intermediary necessary. Probably you won't send a postcard to some child you've never met in Shanghai, make a phone call to a random farmer in Ukraine or use a video chat to call random Venezuelans on the Internet, but you can and that's why these networks are so powerful.
I'd argue mobile phones are as important as the other networks you mentioned - instead of finite amount of endpoints, suddenly *everywhere* was in the network
Well, if we're going to be pedantic, then you should make room for the Telegraph network which served a similar function between the postal and telephone networks (and later the internet) as documented in Tom Sandage's _The Victorian Internet_.[1]
Yeah, no. I have thought about this but the problem is that the lay person cannot use a Telegraph. Yes, of course they can go to an office and send a telegraph message, but that's different because now that's clearly mediated and what I came up with is that the crucial thing is the lack of mediation.
If the UPU begins a thousand years earlier that falls by the same reasoning, a thousand years earlier too many people aren't literate, so they need to have their letter written by someone else, and the recipient must find someone to read it - but by the time of the UPU literacy is widespread.
The thing these have in common is that they're connecting all the people. There is no intermediary necessary. Probably you won't send a postcard to some child you've never met in Shanghai, make a phone call to a random farmer in Ukraine or use a video chat to call random Venezuelans on the Internet, but you can and that's why these networks are so powerful.
[1] https://en.wikipedia.org/wiki/The_Victorian_Internet
If the UPU begins a thousand years earlier that falls by the same reasoning, a thousand years earlier too many people aren't literate, so they need to have their letter written by someone else, and the recipient must find someone to read it - but by the time of the UPU literacy is widespread.