BlogNewsTruecaller Insights: New Spam Filters From Us. Less Spam For You.

Truecaller Insights: New Spam Filters From Us. Less Spam For You.

Kim Fai Kok

May 18, 20163 min readEdited on Jun 15, 2022

Millions and millions of people use Truecaller every single day to improve their lives by reducing unwanted calls and saving their time. We’re incredibly proud to have built a strong and committed community that contributes daily to give back to each other by reporting and tagging numbers that are considered as spam or unwanted

. Our belief has always been that we can only solve this global problem if the community comes together.

Recently, we have made some significant changes to our spam filter algorithm in order to improve the call blocking experience. The results have been staggering.

Before the changes, our spam lists were country based – which means that the algorithm computed a top 2000 list of spammers per country, and top spammer lists were updated daily.

This presented one huge challenge – ensuring a relevant spam number list for each user (while keeping the list small enough for phone capacity, at 2000 spammers per user).


For example, looking at the Indian map above, it is easy to see why a national top spammer list, containing a spammer from Delhi, might not be relevant for a Truecaller user in Mumbai.


Indian callees receive a huge amount of spam calls, more than 300 million per month! Delhi users alone receive a massive 60 million spam calls every month (15 million per week.) So, to ensure that the top spammer list is relevant for each user, we decided to narrow down the list to regional level.


The effectiveness of our spam filters varies by market – in the U.S. and India, around 70% of spam calls are captured by Truecaller’s automatic spam filter, whereas this percentage is in the high 90s for markets like Nigeria and Egypt. Also, since the introduction of the new spam filter algorithm, the effectiveness of the spam filter has increased substantially.

In India and the U.S., the percentage of spam calls captured by the new algorithm is around 79% and 75% respectively, versus a previous value of around 66%.


Finally, looking at the top 10 regions (by number of incoming spam calls), we can clearly see the improvement in spam filter effectiveness after the introduction of the new algorithm.

To illustrate, the percentage for Delhi goes up from 53% to 70%. Gujarat sees an even more dramatic improvement (from 58% to 83%). This improvement factor, not surprisingly, is more muted in regions that already had a high spam effectiveness, such as Madhya Pradesh and Andhra Pradesh, prior to the introduction of the new algorithm.

What does this mean for Truecaller users?

  • Able to stay more protected against local spammers
  • Being able to identify more spammers even though they aren’t connected to Internet
  • Less data usage

In conclusion, our new spam filter algorithm using a regional focus is already showing massive benefits, stopping millions of spam calls each week.

But we won’t stop here. We will continue to work on improving the way Truecaller captures spam in order to help make our users live spam-free, and make Truecaller a more delightful experience.

What is Truecaller Insights?
Being data driven is an extremely important trait for Truecaller, throughout our app lifetime we have discovered and predicted amazing trends just through our internal statistics. Truecaller Insights aims to provide relevant, data-driven articles about market trends. The insights come from a mix of engineers, data scientists and marketers who put their heads together to tell data stories in an entertaining and informative way.

Kim Fai Kok

May 18, 20163 min read


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