How does Truecaller know our name?

The information portal for safe cell phone use

At the moment mobilprü is about phone apps. More precisely: about apps with which you can not only control the telephone function on the smartphone, but also receive information about unknown callers. That can be practical: An unknown number calls my cell phone and my phone app immediately shows me whether it is a telemarketing company, a survey institute or a car repair shop.

But how does the app know all the unknown numbers? This question decides whether apps with “caller identification” are a total loss of privacy or whether they enrich and protect it by recognizing and blocking annoying calls.

Spam protection with privacy: possible, but seldom

The “Should I accept?” App, the winner of our small test series, shows how the latter works. The service with the unfortunate name relies on community: Every user can report company telephone numbers - above all, of course, spam callers and telemarketers. You can also provide useful public numbers.

The app does not access its own telephone number, nor does its own telephone book. Spam protection without having to get naked is possible.

Drupe: Improved at short notice

Of course, we also tested the two elephants among the services for caller identification, "Truecaller" and "Drupe". The good news: both largely adhere to the General Data Protection Regulation. The days when the user's entire address book was simply uploaded, combined there into a gigantic telephone book and made available to all users seem to be over, at least in Europe.

With the “Drupe” app, however, it has only been for a few weeks. When we were still downloading the app from the store on June 21, 2018 to test it, it happily transferred the entire address book including e-mail addresses - if the "caller identification" function had not been switched off beforehand. After we informed the company, a version update came promptly in which the said function is no longer available. According to Drupe, she has been hired across Europe.

The function still exists in non-European countries. If you have the bad luck in this country, for example, to be in the address book of a US acquaintance, you could very well end up in Drupe's community telephone book. Namely when this friend uses the Drupe app with the "Caller identification" function.

Open at the bottom: Caller identification the hard way

Other successful services that we haven't tested yet continue to read the address book and share it with other users. At least if you can believe the respective data protection declarations. These include the dialer from "Simpler Apps", the caller from "" and the "CallApp" from the company of the same name.

It doesn't matter how clean the consent and information process is: Since this involves the numbers, names and e-mail addresses of third parties, this approach is prohibited on principle. Or did you get permission to share from every entry in your phone book?

The comparison with messengers and social networks, where everyone uploads their address book, does not work here. With them, contacts are usually only matched to identify other users. In the case of the phone apps, contact details are not only saved, but also made available to other users.

Truecaller: data protection light

The Truecaller service is now trying its hand at a model that we would call “caller identification plus a bit of data protection”. Only the numbers and names of the users themselves end up in the shared telephone book of the service.

So if you want to enter your own name plus telephone number in a global telephone book, you can also see the numbers of all other 250 million users. At least everyone can decide for themselves here.

#AppTest #Spam #Telephoning
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