Ask HN: How can I buy non-VoIP phone numbers?

I'm looking to set up something related to a service like https://clerk.chat. This would require the ability to obtain phone numbers that can receive SMS codes from banks, government agencies, and tech companies, many of which block VoIP numbers like Twilio, Google Voice, etc.

Anyone ever worked on something like this or have any idea where to start looking for providers? The industry itself seems rather opaque.