Spam calls from telemarketers

Post inspired from another post. What is your method to deal with spam calls? What I have tried and it worked well for me: Get Android phone. Get Truecaller. Block all calls not in the phone book. Do this for a month. All callers will find your number unresponsive and remove you from calling lists. If you are expecting unknown calls like Swiggy/Zomato/Amazon, unblock momentarily till the delivery. Your number has been public. Your telecom sells it, bank sells it, Universities sell it, discoms sells it. Your number is sold as soon as you buy a new SIM from a telecom. If there's a buyer, even you wud sell your number for a good price. Weird world. Even TRAI is useless and doesn't execute fines plus the onus is on you to complain and report via a stupid needless form for every spam. In India, Truecaller is a 99% good solution.I know some friends in sales & call centers who mentioned they don't wanna waste effort & time with non-converting leads. So they update their calling lists & non-responsive numbers are filtered out. So every 6mo, I block all unknown numbers and monitor my spams. Worked well.