I am using e-mail since about 2000's. Passing throught MSN video calls; early Google Talk; then came Skype; even Whatsapp; finaly but not last Hangout. All "for free" +plus no-ads.
Provided by some company via a paid service or ads. Most commonly an ISP monopoly or oligopoly, or a large service monopoly, in nearly all nations. Even if you run your own email server, it's not free, you're paying for the network access to do it.
> MSN video calls
Subsidized by an operating system monopoly.
> Google Talk
Subsidized by a search monopoly.
> Skype
Which was never able stand on its own profitable two feet. It was subsidized first by investor money, then by an auction monopoly, then by an operating system monopoly.
https://www.nationalgeographic.com/science/2018/09/news-muse...