The second link there is much more meaningful.

I actually did see the tweet in full it turns out. It's just that there's not much content so i figured "oh it's one of those twitter thread chains i can't read".

Good post, also they use Quectel because it allows changing IMEI with a single AT command.

this is a required hack, for any founder

SO much value in being able to root out garbage sales calls

Same. The only downside is local contractors will also screen you, but most call me back when I leave a message insisting I'm local and give my address.

> all landline residential numbers start with an area code that starts 02 for London and 01 for the rest of the coountry

02 dialling codes are used in more than just London; Northern Ireland and Coventry phone numers start with 02 for example.

Yes. There's no obvious way to differentiate between a mobile and a non-mobile number in the USA. Numbers are "somewhat local" in that the first three digits usually correspond to a strict geographical area. However that's not a guarantee since if someone moves to another area/state these days the mobile providers will let them keep their number.

Also traditionally American cellphone users pay to receive calls, which will blow the mind of a Britisher.

Denmark went 2 steps further: we no longer have area codes and all phone numbers can be mobile or landline.

In old days the numbers were distinct but these days the overview just says "mostly mobile" or "mostly landline": https://digst.dk/media/x3tmvqsl/nummerplan_2020_farver.pdf

Cell phones evolved differently.

The UK (and Australia) set up a separate prefix for mobile calls. They were more expensive to call. You also knew if you could text someone because it was a mobile number.

The US had analog cell phones for longer and they were introduced to be in the same area code so counted as a "local" call (vs "long distance") for anyone calling that number. The receiver also paid to receive that call, originally.

I honestly don't know how landlines are charged now. It's been probably 20 years since I've had one. Some cheaper cell phone plans might have limited minutes but it's way more common to have unlimited talk and text to any US domestic number (landline or cell).

Oh we had 1800 that were "toll free" meaning they didn't incur long distance charges, originally but this doesn't really apply now. Also, they ran out of 1800 numbers so pretty much anything 18xx is a toll free number.

Note the 1 in front too. That's also a US thing. It technically indicates you're making a "long distance" call. More specifically, you're specifying an area code.e Modern smartphones don't generally require you to type in the 1. Old phones did.

So if you were on a 718 number and call someone else on a 718 number, you could just use the 7 digits of their number. This isn't something people really do anymore. But if you had to call a 646 number you'd put in 1-646-123-4567 back in the day.

By the way, the cell phone numbers being in a given area code explains this joke [1].

Oh the UK/Australia system had its issues too, like it mattered if you were calling from Vodafone to another Vodafone user or if it was an Orange or BT cutstomer because you were charged differently and it could count against different free minutes pools. And you really had no way of knowing.

I don't believe the US had that kind of issue or, they did, it was so long ago that nobody remembers.

[1]: https://xkcd.com/1129/

The funny thing for me is that I still have the phone number I had when I was growing up, which is for a state halfway across the US. Most of my spam calls are in the area code of my phone number, making them pretty easy to recognize since I dont really know anyone from that area code anymore

Twitter is inconsistent for me. From the mobile (FF, not authenticated) it's blocked but from desktop (FF, not authenticated) is visible.

Thanks! I was assuming it was a chain with more details than i saw there.