Truecaller is an international phone directory of sorts that covers both fixed-line and mobile phones. It picks up numbers in two ways: by partnering with national phone directory services, and by getting users of its apps to upload their own smartphone address books.

The idea is that, when a user sees an incoming call from a number they don’t recognize, they can use Truecaller to check who it is. The company maintains a community-driven list of known spammers, so miscreants get flagged up quickly.

Truecaller spokesman Kim Fai Kok told me on Tuesday that, while the user-base spans 128 countries, the vast majority of those 10 million users reside in India. Although this was initially surprising, it does make sense given the company’s platform trajectory.

“We developed first for Nokia,” he said. “Nokia smartphones have always been big in India, and when people move onto Android and iPhones they bring the good apps with them.”

The service’s popularity in India has not been without controversy, with reports last year pointing out that some senior politicians were in Truecaller’s database despite having unlisted numbers – this was down to the ability of Truecaller’s users to upload their personal address books, which clearly contained those numbers in some cases. That said, the company points out that its customers use numbers to look up names, not vice versa (unless the numbers come from public directories anyway), making this less of an issue than it may at first seem.

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