There is at least one, and probably a lot more, huge "scam center" in India that makes thousands of calls a day using every scam approach in the book: "The Windows Support Team", "Free Vacations", "Debt Collection", "Free Medical Equipment", etc., etc., ad nauseum. Even if you have the ability to block the Country Code for India, which is 91, it won't help much as it is hardly ever included in their spoofed numbers.
How will an invalid number be identified? Why is such allowed? The consumer seems to have less and less protection. We are on the DO NO CALL list and we still get numerous calls from Betty, who wants to clean our carpets and many others, including calls from this bogus number.
You need to understand what the DNC is and isn't. It's the equivalent of the cheapest, flimsiest, most useless padlock available. It will only "protect" you from honest people and those that never come on your property. It will do nothing to protect you from the errant moth that brushes against it and it certainly won't protect you from a dedicated thief.
Whether we should HAVE to protect ourselves is irrelevant. Thieves are out there and they thrive on those who think the DNC will protect them. Call blockers come in many forms and range in price from reasonable to downright free. Get one with "First Ring Suppression" and you'll never know these people call until you check your call log.
The DNC only works for law abiding telemarketers. It will not stop dermined criminals or scofflaws. Invest in a call blocker and DO NOT pick up on call numbers you do not recognize. It would be a good idea to block the 202 area code. The Indian and Pakistani scammers just love to spoof that area code.