American phones were slammed by an estimated 2.49 billion robocalls in the month of May, a 6.3% increase over April's total to tie the monthly record for the nation's top robocall volume.

The 2.49 billion total for May equals an extraordinary 930 robocalls placed every second somewhere in the U.S. during the month. These results come from the latest National Robocall Index™ report released today by YouMail, Inc., the leading provider of intelligent telecom services for consumers and small businesses.

The Robocall Index is a free monthly report that tracks robocall volumes across the country. American businesses and consumers have endured just less than 19 billion total robocalls over the last 12 months The 18.97 billion total over the past year represents nearly 80 robocalls for every adult in America.

The data is based on calls blocked and/or reported as spam by millions of YouMail subscribers nationwide. Having answered billions of calls for its users, YouMail uses algorithms to detect any automatically dialed calls and then aggregates that call data into the Robocall Index.

Outbound Robocalling "Lowlights" from May

As in past months, debt collections continued to be the primary cause for robocalling in May. YouMail suggests that the Robocall Index may serve as a potential economic indicator for some area codes due to its high correlation with payment reminders and debt collections.

Debt collectors for banks, retailers, student loans and telecom providers made up 16 of the top 20 robo-dialers in the month of May, or 80% of all robocall sources. Other leading sources of robocalls included education service providers and telemarketers.

Remarkably, one credit card company has held the top spot as the most prolific robocaller for eight straight months, dialing 30.2 million American phones from a single phone number in May – or 63% more calls than the second most prolific caller, a retail debt collector.

Columbus, OH, retook the lead as the most-prolific robocalling city with 78.4 million calls placed in May, passingNew York to lead the list of the Top 20 Cities that Made the Most Robocalls. Other cities on the top five most-prolific robocalling list for May included New York (71.0M), Dallas (62.6M), Los Angeles (62.0M), and Chicago(50.3M).

Inbound Robocalling "Lowlights" from May

Atlanta led the YouMail 50 Most Robocalled Cities in America™ list for the sixth month in a row, receiving an estimated 105 million robocalls in May, up 8% from the previous month. Atlanta alone is on track to get over 1 billion robocalls this year. Other cities making the Top 10 List included Dallas (93.7M calls), New York (89.7M),Chicago (89.0M), Houston (84.6M), Los Angeles (76.0M), Baltimore (58.5M), Newark (50.1M), Philadelphia(44.0M), and Detroit (42.4M).

The newest entrants to the 50 Most Robocalled Cities list for May were Long Beach, CA (#49 with 992,500 calls received) and Minneapolis (#50 with 325,000).

Atlanta's 404 area code topped the 40 Most Robocalled Area Codes Per Capita, with an average of 38.0 robocalls received per capita/month on average. The other Most Robocalled Area Codes Per Capita included Baton Rouge 225 (32.7 calls/month) Washington, DC 202 (26.8), Memphis, TN 901 (19.7) and Macon, GA 478 (19.5).

"Robocallers get in the way of your productivity, whether you're a consumer or small business owner," said Alex Quilici, CEO of YouMail.  "As robocall numbers continue to rise each month, YouMail's free Smart Blocking feature protects its subscribers from being harassed by making spammers and other unwanted callers think their number is no longer in service."