My company's main line is a Google Voice that forwards to my cell; I never give out my cell. But this is preventing me from using some services and products (Vercel, DocuSign, etc.)

I’m curious about the reasons behind this. Is it primarily technical (spam prevention, deliverability issues), business-driven (carriers pushing back on VoIP), or just an easy way to block disposable accounts? Is something more dystopian going on, like some kind of behind-the-scenes lookup of my "true" info if I provide my cell?

Also, if anyone has insight into how companies technically detect and filter VoIP numbers at scale, I’d love to understand that side too. E.g. what lookup info via Twilio causes a number to get rejected? I assume it is the 'type' from Twilio Line Type Intelligence (or equivalent)?

https://www.twilio.com/docs/lookup/v2-api/line-type-intelligence