I got this diabolical idea after remembering that my late dad used to work at a phone company back in the 70s. Note: this will require access to their PCs and their phone service.
I’m not sure if this will still work on modern phone systems but if it does it will be super annoying. Basically, there is a way to put a phone system into “test mode” where it calls itself using test tones, and after the test is over plays an annoying tone just to make you hang up again to prevent talking while in test mode. Thus the scammers keep callflooding themselves with annoying beeps. XD
The problem is I don’t know about India’s phone system or the test “Ringback” numbers used there (serious digging will be required as they are not meant to be public, to prevent the above).
(There are several other test systems, but that one would be the only one that could produce interesting results)