In the U.S., the National Do Not Call Registry is https://donotcall.gov/. There's been a change in the registry and you no longer have to renew your registration every five years - your registration is permanent until you change your phone number.
What frustrated me for a long time was that there was no easy way to file a complaint. Now there is, right on the same Website. Most of the information requested is on the Caller ID on my phone, so it just takes a minute to file a complaint. I don't know if filing a complaint does any good, but it feels better once I've done it.
I had been getting recorded calls from "Obama Stim," offering to refinance my house. It felt good to report these guys, since they had used the name of my President in vain.