(NEXSTAR) – Sick of unwanted calls and texts bombarding your phone? Your first stop is probably the national Do Not Call Registry, which threatens telemarketers with a hefty fine if they contact people on the list.

The official Do Not Call list has grown to 221 million phone numbers and counting, the Federal Trade Commission says – so why haven’t spammers, scammers and robo-callers gone out of business yet?

The answer may be hiding in the fine print. The Do Not Call list doesn’t actually block everyone from reaching out to you unsolicited. The FTC rules still allow calls about political campaigns, charities, debt collections and surveys to go through, even if you’re on the registry.

Telemarketers are also still allowed to reach out to you with a sales pitch if you’ve recently done business with the company.

Then there’s the fact that not everyone plays by the rules.

It’s like when you put up a “no trespassing” sign on your property, explained Alex Quilici, CEO of call blocking service YouMail.

“The good guys aren’t going to trespass on your property, and the guy who’s going to burglarize it doesn’t care. We see the exact same thing with the robo-callers and the Do Not Call list. The good guys – like your credit card company – they’re not going to tele-market to you … but the scammers are trying to steal from you. So who cares about a penalty for making a phone call? And so that’s why it doesn’t really work.”

Legitimate companies that violate the Do Not Call rules can face a fine of more than $50,000 per call, according to the FTC.

But illegitimate, bad actors have actually used the registry to their benefit in the past, Quilici said. “They specifically targeted people whose numbers were on the ‘Do Not Call.’ And they did that because they were more likely to have those people answer.”

You can sign up for the Do Not Call Registry here. If you want to reduce unwanted calls even more, the FTC recommends looking into call-screening apps.