Hot take #2:
As a libertarian, I would voluntarily fund the use of military force against scam call factories in India. Literally drop a bomb on the office and kill all the parasites inside.
Discussion
With respect to peoples' freedoms, it'd be a better way to solve the problem than with censorship of phone calls.
Before you write an article and call every scammer a parasite, remember that some parasites are abducted and stripped from all personal belongings to forcibly work as a scam callers. Sometimes scam callers just try to survive.