There's one missing piece in that article, and it's the CNAM database (US only).
CNAM is the database that carriers use to give you alphanumeric caller ID ("SMITH JOHN" instead of "+1 (555) 123-4567"). Many carriers don't display this data as far as I believe, but most of them make it available.
Querying that database isn't free, but you could probably find a way to do it for a few hundred numbers relatively cheaply. People's names and emails are often similar, so you could probably figure out an algorithm to give you the most likely candidates.
The data is often wrong in interesting ways (I've seen everything from deadnames to people's exes they still share a plan with), but it is still pretty useful.
At least in T-Mobile's customer UX, you can set this to whatever you want per line [1]. Have tested by changing line CNAM and querying with Twilio number lookup [2]. You're supposed to be honest wrt person's name, but it's honor system.
The point of that database is to display a recognizable name to the people you call, so that they know it's you. A recognizable name isn't always the one on your birth certificate (particularly in the US). There are also businesses, who want their business name there.
As Brit-expat+US-resident (since 2012) T-Mobile got my SSN when I signed-up for my
pre-paid first mobile phone plan in 2012. Paying $50/mo was quite a shock when equivalent (or rather: far superior) service was available in the UK on a PAYG (not even pre-paid!) basis for £10/mo.
...and now I'm on a $110/mo postpaid plan because eventually you get tired of the limitations and just grin-and-bear-it.
So that they can seamlessly upsell you on upgrading to a new phone that you'll pay off in installments over the next couple years.
Also, many postpaid plans (like my home ISP) require SSN because they are providing you service on credit. Postpaid cell paone plans have been the "default" in the US for a long time, though prepaid seems to be gaining market share.
We are kind of assuming a lot when a $100 a month account obviously requires a credit check.
They require a SSN because people don't care and it makes it cheaper to offer the accounts, not because it would actually be a big problem to sell internet service without credit checks.
The credit checks, the carriers would tell you, are to try to protect them against people who sign up for service with a "free" phone on a 3 year commitment (phone paid for in part by 36 installments of credits) and then they stop paying the bill. Sure the phone will be blacklisted and remain SIM-locked, but could still be used on Wi-Fi and either way the carrier can't have it back and is therefore out their cost of the phone.
Now, as for why they still do the same credit checks when you bring your own phone, I suspect "Because F you, that's why" is the gist of it.
CNAM is the database that carriers use to give you alphanumeric caller ID ("SMITH JOHN" instead of "+1 (555) 123-4567"). Many carriers don't display this data as far as I believe, but most of them make it available.
Querying that database isn't free, but you could probably find a way to do it for a few hundred numbers relatively cheaply. People's names and emails are often similar, so you could probably figure out an algorithm to give you the most likely candidates.
The data is often wrong in interesting ways (I've seen everything from deadnames to people's exes they still share a plan with), but it is still pretty useful.