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11% Monthly Robocall Decrease in April Confirms Robocallers Are Paying Attention To Upcoming STIR/SHAKEN Deadline
[April 30, 2021]

11% Monthly Robocall Decrease in April Confirms Robocallers Are Paying Attention To Upcoming STIR/SHAKEN Deadline

NEW YORK, April 30, 2021 /PRNewswire/ -- RoboKiller, the app that eliminates 99% of spam calls and  text messages, reveals Americans received an estimated 5.7 billion spam calls in April 2021 - an 11% decrease from March. April's 6.6 billion total spam texts decelerated by 10% from March's 7.4 billion.

April's robocall decrease is not a surprise, however. Historically, April and May have shown flat or decreasing levels of total spam calls in the U.S. because scammers tend to push IRS & tax season phone scams in February and March ahead of the standard tax deadlines in April.  It is also notable that spam call volumes continue to grow on an annual basis and represent a record high for the month of April.

April 2021's spam call trends may also be related to the upcoming STIR / SHAKEN (Secure Telephone Identity Revisited (STIR) and Signature-based Handling of Asserted Information Using toKENs (SHAKEN)) implementation deadline, which is designed to combat caller ID spoofing on phone networks in the United States, and recent announcements by large U.S. carriers that have already implemented the framework. However, given the continued annual growth and seasonal factors cited above, it appears unlikely that Americans can expect meaningful decreases in total spam calls in the months ahead.


Top Five Most Spam-Called States:


Total Estimated Spam Calls

Estimated Spam Calls Per Person


628 million



495 million



357 million


New York

221 million



217 million


Top Phone Scams:
Vehicle warranty-related spam calls represented 20% of total robocalls during the month of April - an 11% increase from March. Vacation-related (which includes fake offers for cruises, timeshares, etc.) spam calls came in second and made up 8% of spam calls for the month, while health insurance-related spam calls were 7% of total robocalls.

Top Five Most Spam-Texted States:


Total Estimated Spam Text Messages

Estimated Spam Texts Per Person

New York

692 million



678 million



581 million



317 million



306 million


Phone Scammers Are Paying Attention To The Approaching STIR/SHAKEN Deadline
April 2021 spam call and text trends indicate that phone scammers are paying attention to the STIR/SHAKEN framework because it is designed to combat a common tactic they use to make their robocalls nearly untraceable - caller ID spoofing. The STIR/SHAKEN framework uses digital certificates to authenticate the true origin of a phone call and inform use cases such as labeling potential spam calls as "scam likely." Signed into law in 2019 by the Pallone-Thune TRACED ACT, STIR/SHAKEN requires all major phone carriers to adopt this framework by June 30th, 2021. Smaller phone carriers must adopt this framework or implement a robocall mitigation plan by 2023.

Despite large carriers such as T Mobile, Verizon, and AT&T recently announcing adoption of the framework ahead of the June deadline, Americans are on track to receive more than 70 billion spam calls in 2021 - a 28% increase from 2020. High spam call volume from January to March 2021 indicates that scammers may already be looking for new ways around the STIR/SHAKEN system - and succeeding. The recent explosion of spam texts also reflect increased efforts by phone scammers to find new ways to steal from Americans over the phone.

Will STIR/SHAKEN Stop the Spam Call Problem For Good?
The STIR/SHAKEN framework is a great first step in a collective effort to stop robocalls, but it will not stop them entirely. It's important to note that the framework itself won't block spoofed robocalls, it will  only identify whether the origin of an incoming call has been verified or not (which does not necessarily correlate to whether a call is spam or not). Another limitation of STIR/SHAKEN is that it works only with IP-based service providers, so not all networks will be able to adopt this framework, even after the 2023 deadline. This can quickly create loopholes for scammers to work around the authentication.

RoboKiller's cutting-edge call blocking technology closes the possible loopholes in the STIR/SHAKEN framework by:

  1. Identifying and blocking incoming spam calls versus just identifying them.
  2. Leveraging advanced technology such as audio fingerprinting that goes beyond the phone number to analyze the intent of the caller before the recipient answers the phone.

RoboKiller Adopts STIR/SHAKEN Framework for Consumers and Businesses
Identifying the true origin of a spoofed call has been one of the most technologically challenging elements of spam call blocking. The STIR/SHAKEN framework offers exciting developments in the ability to identify caller ID spoofing as it's happening.

Since the framework's creation in 2019, RoboKiller has been working diligently to integrate STIR/SHAKEN into our already 99% effective spam call blocking algorithm. RoboKiller users can expect continued or even elevated levels of spam call blocking effectiveness following the June 30th deadline.

To help accelerate STIR/SHAKEN's impact and protect more Americans from robocalls, RoboKiller recently released its new Enterprise API for businesses of all sizes. While not all organizations will be technically or financially able to implement full STIR/SHAKEN by the upcoming deadline, businesses of any size can implement a Robocall Mitigation Program, including blacklists, reputation scoring, and other mechanisms, all of which can be provided by RoboKiller's new Call Confidence API.

"Government efforts like STIR/SHAKEN are a positive step towards putting an end to robocalls," said Giulia Porter, Vice President of RoboKiller. "The continued rise of spam calls in 2021 indicates that scammers are taking the framework seriously, which also likely means they'll be quick to exploit the known gaps. We're excited about the opportunity STIR/SHAKEN brings RoboKiller and its users for continued advancements in our all-encompassing solution to spam calls."

Tips On How To Stop Phone Scams:

  • Don't answer phone calls from unknown phone numbers, especially those that call or text at odd hours.
  • Never provide personal, banking, or sensitive information over the phone to any caller.
  • Don't follow any prompts like "Press 1" or click any links.
  • Download a spam call and text blocker like RoboKiller to equip your phone with the latest phone-scam-fighting technology. Apps like RoboKiller use global databases of millions of known scams to prevent them from reaching you in the first place.

RoboKiller's Data Insights
These national robocall and spam text insights are provided by RoboKiller, the only app that helps eliminate 99% of spam calls in the United States. RoboKiller's Robocall Insights is powered by its global database of millions of known phone scams and audio fingerprints. This data is estimated by monitoring observed robocall and spam text trends for Americans who have trusted RoboKiller to stop their spam calls and has been featured by major media publications since its release in 2018. 

For a comprehensive analysis of robocall trends in specific cities, states, and area codes, details on particular phone scams, or any other related custom inquiries, please contact RoboKiller's robocall insights team here or at

With more than 12 million downloads to date, RoboKiller has been named a leader in technical and mobile achievement by the Webby Awards, Media Excellence, Best in Biz, and more. RoboKiller was also named the most effective solution to robocalls by the FTC as the winner of the most recent Robocalls: Humanity Strikes Back competition. RoboKiller is available for download on the Apple App Store and Google Play. To learn more about RoboKiller, visit

About RoboKiller:
RoboKiller is the leading independent spam call blocker in the United States. RoboKiller's predictive spam call blocking technology uses A.I. and machine-learning to intercept an incoming spam call in less than 0.01 second. RoboKiller then deploys its army of spam-call-fighting Answer Bots to waste scammers' time and resources, preventing them from placing thousands of spam calls each minute. Since its launch in 2017, RoboKiller has helped more than 10 million Americans prevent approximately $140M losses to phone scams and live their lives spam-call-free™. RoboKiller, a Teltech brand, is a division of Mosaic Group, an IAC Company (NASDAQ: IAC).

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SOURCE RoboKiller

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