The “Do Not Call” Registry doesn’t always work. Here’s what does…

Signing up for the federal government’s Do Not Call Registry was supposed to protect us from unwanted telemarketing phone calls. But a lot of unwanted calls still sneak through, and it’s only getting worse. Inexpensive international Internet-based calling allows telemarketers to evade US laws by contacting us from overseas. And certain callers, including pollsters, politicians and charities, are exempt from the National Do Not Call Registry restrictions.

You still should register your landline and cell-phone numbers with the Do Not Call Registry (DoNotCall.gov) because it does reduce unwanted calls. But here are four additional steps to further block these calls…

1. Stop writing your phone numbers on forms and entering them into Web sites. Retailers, Web sites, charities and political organizations often ask for phone numbers, but that doesn’t mean you have to provide them. Handing out phone numbers to such organizations increases the odds that the numbers will end up on additional call lists. An e-mail address should be sufficient when contact information is needed.

When a Web site won’t let you proceed without entering a phone number, supply a fake one starting with “555” after the area code. (No real numbers start with 555.)

Exceptions: Do provide your real phone number(s) to doctors’ offices, insurers, credit card providers and other organizations that might have a legitimate reason to contact you quickly.

2. Sign up for Nomorobo—if your telecom provider is eligible. This is a free service that recently won the top prize from the Federal Trade Commission for coming up with a technological solution to reduce the number of robocalls.

Incoming calls to your phone number are routed not just to your phone but also to Nomorobo’s computers. These computers very quickly determine whether the call is from an automatic dialer—a tool used by many of the worst telemarketers to call several numbers quickly—and hang up on the caller after the first ring if it is.

Nomorobo does allow legitimate ­automated phone calls through, such as reminders about doctor and other ­appointments.

Unfortunately, you can use Nomorobo only if your phone provider and/or cellular provider offers a service called “simultaneous ring,” which allows calls to one phone number to ring at a second number as well.

Most Internet- or cable-based telecom providers offer Nomorobo, but many ­cellular and traditional landline providers currently do not-though that could change if Nomorobo ­continues to gain popularity. At ­Nomorobo.com, click “Get Started Now” to determine whether you can sign up.

3. Block calls from troublesome phone numbers. Some telecom providers allow their customers to block incoming calls from specific numbers, perhaps by entering a code immediately after receiving a call from someone you don’t want to hear from again. Contact your provider(s) to see if such a feature is available to you.

Unfortunately, blocking individual phone numbers won’t stop the most unethical telemarketers—they tend to use “spoofing” technology to make their calls appear to come from a different phone number each time.

Because of this limitation, it’s usually worth blocking individual numbers only if your phone provider lets you do so for free.

Also: Some telemarketers block their own numbers so they don’t appear on your caller ID at all. Some phone-service providers offer the option of blocking incoming calls from callers that have blocked numbers—ask your provider.

4. Ask legitimate organizations to “put me on your do-not-call list.” Pollsters, politicians and companies that place unsolicited calls generally are required to maintain their own do-not-call lists. Ethical organizations comply with requests to be placed on these lists. ­Exception: Prerecorded-message calls typically include instructions for opting out of future calls, usually by pressing a key on the phone’s keypad. Do not follow these directions if the automated call is from an unknown or a potentially untrustworthy caller—doing so can lead to an increase in call frequency.