> Is there a way to tell if a phone number is from a VoIP service?
Comment below was written for voice calls, SMS may be more tractable.
(Assuming US numbers) Yes, but it costs money. You can get (free) data from NANPA on which carrier was originally allocated the number, but it may have been ported.
But, the big blocker is a lot of source numbers are spoofed; not sure if a spoofed landline is less spammy than a spoofed VoIP; although an unallocated number is probably more spammy (OTOH, allocation data isn't always timely updated). If you could get the equivalent of Received headers, that would be a lot more useful, but that's not really an option.
Having worked in products using VoIP stuff, you’ll hit issues with 2FA requests from some apps. The big names have their own shortcodes, but many smaller apps use a generic VoIP number from Twilio or similar.
Is there a way to tell if a phone number is from a VoIP service? It'd be great if I could just block those wholesale, as well as any text message that's sent from an email address.