Even tried to use a new number, worked for a year or two and it got leaked to some telemarketer.
With the effort involved to change my number again. I decided to try a new tactic; waste their time.
They call me, I identify it is spam(eg first name instead of real name) and ask them to hold and then go silent/ghost until they hang-up.
I feel guilty to hear "sir, sir, voice of despair sir... beep beep beep" because I worked in a call center and understand these guys just want to make a living. I tried to be nice and asked my number to be removed, no luck.
I engage and then waste their time and now suddenly I stop to get telemarketer calls?! On a side-note I feel like I started to receive more SMS spam. So I'm now at the point of wanting to opt-in so that they can call me to waste their time. _sigh_