Is it possible they can track your number and how do you hide your number. Also is this illegal?
DONT use your real number, use FireRTC, Google Voice, or TextNow.
DONT be under the impression that caller ID blocking works, as it wont, when you dial 18xx numbers.
DO spoof your caller ID on FireRTC.
DO use an area code outside of your own.
DO rotate/shuffle numbers
Is it illegal? Depends on where you live. Some could call it harassment if you constantly call them. Some could call it criminal mischief if you prevent them from doing business. Some could call it hacking if you use malware to invade their networks.
Will they prosecute you from India or another foreign country? Unlikely. I'm not an attorney though.