The Do Not Call Registry, explained

What it is

The National Do Not Call Registry is run by the FTC. You add your landline or mobile number at donotcall.gov once, and it no longer expires; it used to require re-registering every five years, but that requirement was dropped in 2008. It takes up to 31 days to take full effect after you sign up.

What it actually stops

Legitimate telemarketers, meaning real companies making sales calls to consumers they don't already have a relationship with, are legally required to check the registry and stop calling numbers on it. For that category of caller, it works.

What it doesn't stop

• Scammers. Fraudulent callers were already breaking the law before they dialed, so a registry that relies on legal compliance has no leverage over them.
• Companies you've done business with recently, who can generally still contact you.
• Political campaigns, charities, and survey calls, which fall under different rules.
• Calls placed from spoofed numbers, which is most of what a site like this one tracks. The registry has no way to stop a call that's already lying about its origin.

Why it's still worth doing

Registering isn't really the point on its own; filing a complaint when a registered number gets called anyway is. Those complaints are what give the FTC evidence to act against telemarketers who ignore the registry, and they're part of the same public complaint data this site is built from. The underlying law that makes those violations actionable is the TCPA. Every number lookup here links directly to the FTC and FCC complaint forms for exactly that reason.

If you want to check whether a number that called you has already been reported by other people, you can look it up here. Curious whether your state runs its own Do Not Call list too? Check your state page.