Scam call centers employ 1000s of people. You just need one of them to talk and collect evidence. The companies pay poorly and have high turnover, so they shouldn’t be hard to find.
The most effective place to stop it is at the "border", and that is what DOJ is doing here.
700 suspected in call center scam [2]
21 arrested [3]
15 arrested [4]
https://www.news18.com/news/india/78-arrested-in-mp-for-invo...
https://www.reuters.com/article/us-india-fraud-usa-arrests-i...
https://www.hindustantimes.com/world-news/telefraud-scam-us-...
https://economictimes.indiatimes.com/news/politics-and-natio...