It's an interesting theory.

From what I understand, I worked in an adjacent field a decade ago, The de-anonymize is actually harder than it should be. a voip user gets service from a voip carrier who contracts service from a larger provider, who gets service from on the the biggest carriers. Noone in that chain wants to be responsible for the people below them. There is an unreasonable amount of trust on many carriers to let the clients choose their own ANI. The systems are not designed with accountability anymore. They're all just a hodgepodge, and the smallest 2 levels of carriers get to charge a premium to let people stay untrackable (like cold calls)