Comment by pragma_x

That's how I remember it.

For completeness, 33.6 required insane levels of signal clarity on the phone line, and was mostly fiction outside of urban and dense suburban areas.

Prior to 14.4k, there were other generations of modems that came before: 9600, 2400, and even 300 baud modems were all you could get in their respective eras. Each of which were cutting edge at the time.

56K (also called V.90 or "V.everything"), leaned into the quantization that happens on digital phone trunks, rather than let the analog-to-digital conversion chew up your analog modem waveforms. The trick here is that the psuedo-digital-over-analog leg from your house to the local exchange was limited by a few miles. Try this from too far out of town, and it just doesn't work. And to be clear, this was prior to DSL, which is similar but a completely different beast.

Oh, and the V.90 spec was a compromise between two competing 56K standards at the time: K56Flex and X2. This meant that ISPs needed to have matching modems on their end to handle the special 56K signaling. Miraculously, the hardware vendors did something that was good for everyone and compromised on a single standard, and then pushed firmware patches that allowed the two brands to interoperate on existing hardware.

Also, line conditions were subject to a range of factors. It's all copper wire hung from power-poles after all. So, poor quality materials, sloppy workmanship, and aging infrastructure would introduce noise all by itself, and even during weather events. This meant that, for some, it was either a good day or a bad day to try to dial into the internet.