To register your phone number in the registry, you can sign up with the form at the official website

You can also sign up on their Whatsapp channel. And another option is to call the hotline at 1-800-071-170.

Using the website linked above you can also file complaints for being spammed.

Perusing the information on the website this is basically to stop businesses from calling you without your permission. It does not affect politicians calling you campaigning for elections, and it does not stop organizations calling you for donations, and it does not apply to people taking surveys. This only applies to businesses spamming you (under certain conditions).

Sorry to say, but with the exceptions being the bulk of the telephone spam there is not much of a point to this registry.

And, now even if they go ahead and sell their list to a bunch of spammers, it probably does not even matter, considering the law doesnt apply to most spammers.