It’s a flatrate. Flatrate only implies the price does not change depending on usage. It does not imply “unlimited” or “no throttle after a certain limit” by itself.

We have a lot of anglicisms in the German language and a few of them have developed meanings different from their English counterparts. The word "flatrate" is one such example. In German it is not taken literally to be a "flat rate" but rather to mean "unlimited".

Yes, I agree with that. We used to have volume and flatrate tariffs for DSL. The flatrates used to be unlimited, then the volume tariffs were removed and the flatrates became volume tariffs with a high (but limited) volume.

Even according to English Wikipedia: https://en.wikipedia.org/wiki/Flat_rate

"A flat fee, also referred to as a flat rate or a linear rate, refers to a pricing structure that charges a single fixed fee for a service, regardless of usage."

Emphasis mine. I'd understand this as there being a service (e.g. high-speed DSL) which you pay a fixed fee for, independent of how much you use it. That does also mean that if you use it more they don't shut it off, because otherwise you're not getting the service independent of usage.

They don’t shut it off. It’s throttled after reaching a certain limit. It’s also illegal to advertise them as “unlimited” (please note: I’m native german, there’s no language confusion)

I am native german and I disagree on that count. It means “flat fee” and not “unlimited”. Local calls for example used to be “flat rate”, they’d cost a fixed fee but disconnect after about 30 minutes or so. (Yeah, I still remember that personally) Flatrates for mobile data never were unlimited, either.

As also a native german, I have to disagree in turn. Story time:

In the 90s, when the Internet started to come into popularity, me and friends were desperately trying to get a connection that didn't cost money per time unit.

For the longest time, with no free local calls like the US had, that simply did not exist, at least via dialup. One option was a "Standleitung", which was almost literally a permanent landline between you and your provider, same signaling and all. Only small providers would usually be talked into it, but then you had to pay a (at the time) huge monthly fee to the Post/Telekom because the line took resources away permanently. Some few people were lucky enough to be able to establish radio channels with their provider (this was long before WiFi was a thing). At one of my first jobs, I got ISDN "callback" as a benefit, which meant that I could call the router, hang up immediately, the router would call back and establish the connection, company would pay!

Finally, after what seemed like an eternity, the first few flatrates appeared. Stay online as long as you want, download as much as you want (at speeds that were still measured in kilobytes/second, but completely adequate for the time). It was definitely Unlimited.

And they were always advertised as “unlimited flatrate”. So yes, that’s my point. Unlimited and flatrate are two orthogonal concepts.

Let’s agree to disagree then, because my point is that they were just called “flatrate”. I even just found this article describing “the first flatrates”, which also just calls it “flatrate” without any qualifier throughout the article, but makes it clear from the beginning that a flatrate is, in itself, unlimited: https://www.netzwelt.de/news/76329-verkehrte-netzwelt-erste-...

Finally, I remember the “Alkohol-Flatrates” that came up in clubs a few years later (and were, unsurprisingly, soon outlawed). Their point was that you could get a theoretically unlimited amount of drinks for your cover charge of typically 15DM or so. In practice that’s a stupid idea of course. I tried it once at the behest of a coworker: The drinks were atrocious, the floor was covered in a thick grime of “free drinks” and the crowd consisted of the type of people who would be attracted to an “alcohol flatrate” in the first place.