Many of these types of Telemarketers use Majicjack and get a US phone number in the area of their choice. The MJ then can be used from India.  Not particularly high tech.

Calls constantly . In the beginning I tried being nice,  then I tried humor, than I tried rough stuff. Nothing works and our Government is busy helping illegal aliens--- So no time for frustrated tax paying   citizens  . Mu advoce block th ecals or just do not answer.

May I suggest an App called Mr. Number? You can set it up to answer and hang up immediately so they can't leave a message. I love it.

Call them back and harass them. I dial *67 so it hides my caller ID and have fun driving them crazy with fear.

3 rings , didn't pick up , no message --scammer