It may start innocently enough: You get a call asking whether you want to buy an ad in a business search directory. Then, a few hours later, you get another unsolicited call ... and then another one.

Soon, you may feel like half your day was spent fielding unwanted calls (or at least checking your caller ID).

Telemarketing or “spam” calls—generally any unsolicited calls that your business gets—may be sucking up more of your time and costing you more in lost revenue than you realize.

A new report from Marchex, a mobile advertising company, suggests that unsolicited “spam” calls cost small businesses in the United States nearly a half a billion dollars in lost productivity each year. And the number of spam calls is rising quickly as more business owners rely on mobile phones: Marchex analyzed its internal data and found that the volume of detected and blocked calls rose 162 percent between January 2013 and January 2014.

“Technology has made it cheaper and easier for spammers to blast out up to tens of thousands of phone calls in a matter of minutes,” the company says in a news release, adding: “Small businesses are more dramatically impacted than large national businesses, which can direct incoming calls at scale through call centers.”

Moreover, the National Do Not Call Registry doesn’t offer protection to business lines like it does to consumers. (Disclosure: Marchex sells software called Clean Call to help businesses screen out telemarketing calls.)

So, how can a business owner reduce the frequency of unsolicited spam calls?

Tell callers to take you off their internal call list.

Telemarketers are required by law to take callers off their list if requested. Rather than brush off unwanted callers or make up an excuse for why you can’t talk, direct them to take you off their internal call list and to not call again. (It’s important to specify that you want to be taken off their “internal list,” because shady telemarketers will take advantage of people who aren’t specific enough in their demands, according to ABC News.)

Register any phone numbers you can on the Do Not Call list.

Even though the National Do Not Call Registry is only meant to protect personal and home phone numbers, you will likely reap more protection by registering your numbers on the list as well. Telemarketers don’t want to get in trouble for breaking the rules, so registering any phone numbers—including any mobile numbers—reduces the odds you’ll get unwanted calls.

Use a call-screening service.

Many phone service providers, including Verizon and Comcast, offer services that allow businesses to block or screen out calls from specific or anonymous numbers, so you’re not wasting your time answering telemarketing calls. For example, a call-screening service may ask someone calling from an unidentified number to either announce their name or to unblock their number. (Of course, businesses that rely on incoming calls for customer communications may want to think twice about making it more difficult for people to reach them.) You may also want such a service on your mobile phone. PrivacyStar is a mobile phone app that color codes calls, allowing users to easily identify whether a call is a telemarketer, a debt collector or a known scammer. It also lets users report abusive calls and texts.

Read more articles on telemarketing. 

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