Yes, there are many APIs available to look up the carrier that services a phone number. You can sort these carriers into categories (landline, mobile, VOIP...) and many services won't accept the number for SMS OTP use if the carrier isn't a "real" mobile carrier, in a somewhat hamfisted effort to prevent fraud.
Well, this has me concerned. There were times when it felt like OpenAI at large was trying to swim one way, while Sam was trying to swim another. In those cases I always thought Sam's direction was the better one. From the outside this seems like a pretty big loss.
Didn't get a mention in the article but Singapore's PayNow is magical. Direct bank-to-bank transfers that operate instantly 24/7, and for free. QR code-based so it's not uncommon to pay at retail outlets with this method; some shops will only accept PayNow or cash, because they're free. You can also pay directly to someone's NRIC (national ID number) or mobile number so you don't have to tack in their bank details or get a QR code from them.
Honestly the only thing that isn't perfect about this system is that there's no hyperlink standard. If you want to pay a PayNow QR code on your phone, you have to screenshot the QR code and then share it to your banking app. Would be nice if you could just tap the QR code. Other than that it's hard for me to imagine a better payment system.
I signed up with my primary email address and phone number (non-VOIP, belongs to a carrier). I even have a WhatsApp account (also under Meta's purview) with this phone number.
I don't have an Instagram account so I tried to create one to try Threads. I used my real name and phone number but it was instantly banned as soon as it was created. I submitted an appeal, which required a selfie taken while holding a piece of paper with my username on it, which I provided. The next day I got an automated email that the selfie wasn't "acceptable" (no further elaboration) and that I was permanently banned from Instagram with no route for further appeal. So overall, not the most seamless onboarding experience I've ever seen.