KnownCalls Frequently Asked Questions

KnownCalls 100% free call blocker software to avoid unwanted calls and accept calls from known callers only.

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KnownCalls Frequently Asked Questions

Postby Admin_N » Fri Nov 24, 2023 3:53 pm

==Where can I get KnownCalls from?==

You can download KnownCalls for free from our website, Google Play Store or Huawei AppGallery.
See links at

==How to set KnownCalls up?==

Download & install the app like you do with other apps. Launch KnownCalls and select the type of blocking you prefer. Give the app the required permissions to do the job. That's it! See more setup details at

==Does KnownCalls work with 2-SIM phones?==

Yes, it can block calls that are in neither SIM.

==What types of blocking does KnownCalls have?==

Depending on your choice, KnownCalls can be blocking calls that are not in your phone's Contacts, not in your phone's Favorites, or all calls when the screen is on (i.e. you're using the phone). Besides, it supports block and pass lists. See more at

==How can I make sure unwanted calls are blocked?==

KnownCalls has a List tab which will take you the call log of KnownCalls. Here's where you can see which calls were blocked or let through, and why.

==I installed KnownCalls but unknown calls are not getting blocked. What's wrong?==

After you downloaded and installed KnownCalls, you need to open it and select which of the blocking methods you'd like it to engage. Make sure that you give the app permissions it asks for, because we only ask for those that are absolutely necessary for operation! If you rejected permissions 3 times, the app cannot ask for them anymore - in that case, we advice to re-install the app to start bring back permission requests.

You can also see the app work status at the top of KnownCalls interface, along with the note if there are some errors.

==My KnownCalls blocks calls from a number that is in the Contacts. What's wrong?==

KnownCalls can block
calls not from numbers not in the Contacts list
calls not from numbers not in Favorites.

If you're using the second type of blocking, only numbers that are in the Favorites will get through.
If that is the case, either use the 1st type of blocking instead, or add the needed numbers to your phone's Favorites.

One more thing to check: Sometimes the number is spelled differently in your Contacts than it is perceived by the phone when it actually calls. See how the number is spelled and change it in your Phone book to the same spelling. That could help too.

==It feels like I'm getting more unknown calls (although KnownCalls does reject them) ever since I got KnownCalls. Is it so?==

It might be connected. Since KnownCalls _rejects_ unwanted calls spammers get to know that your number is valid but that maybe they will get more lucky next time so they keep on calling you. Don't worry about them though - KnownCalls will block them all even if they come in dozens, and still save your time that you'd waste answering those spammers if you got just a couple of calls.

KnownCalls does NOT collect OR share your contacts - it can work without Internet access.
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Re: KnownCalls Frequently Asked Questions

Postby Admin_SP » Tue Dec 12, 2023 8:56 am

==Why not importing external databases to the app?==
We're often asked to add the ability to work with external databases. This possibility will probably be added as an option, but it's important to consider that this scenario of work is impossible without the Internet. This fact contradicts the idea of KnownCalls being completely independent of the Internet connection. The downside of such a working principle is also that the spammer's number will only appear in such a database after someone adds it. In other words, someone has to be subjected to a call from spammers and mark the number as spam. While the number is "fresh," the database will not contain it and, accordingly, will not save you if you or your loved ones become one of the first recipients of such dangerous calls.
Therefore, it is much easier to block all unwanted calls using the Contacts list, white and black KnownCalls lists, which are available now. Meanwhile, if you need to work with external databases, we recommend looking for another application, as this working principle is used in many other applications. 
==Why do I get SMS notifications ? How do I stop receiving SMS?==
To work with SMS, you need a special version of KnownCalls from our website. It will have an "SMS" tab along with "Calls" and "List" tabs. Download it at Note that in this version, SMS will be muted, meaning they will come in without sound notifications. This KnownCalls version can't fully block SMS due to Android platform rules. Blocking would require it to be the main SMS app, which might be inconvenient for some users. We continue to monitor Android's development, and if future updates allow blocking SMS without additional permissions, we'll implement it immediately!
==Does this application work in my country? (or other countries?)==

Certainly! Our free call-blocking app, KnownCalls, has no geographical restrictions. Unlike other apps, KnownCalls operates solely with your phone book, not spammers databases. Thanks to this approach, KnownCalls effectively protects you from annoying spam in any country, wherever you may go.

==Why is the KnownCalls app free? What's the catch?==
There's no catch. This feature is available directly in the iPhones’ system settings. Some Android devices support it as well. We created KnownCalls for ourselves and our employees who lacked contact blocking in their phones. That's why the app is ad-free, safe (doesn't share your data), and free. We add features we need and implement popular user requests over time. 

==My voicemail is getting cluttered after installing the app. What can I do?

To prevent your voicemail from getting cluttered due to missed calls, we recommend disabling voicemail since missed calls will inevitably end up there.

You can set up call forwarding for missed calls to a non-existing number. To activate this feature, dial *67+fullnumber#, and to deactivate, dial ##67#. Make sure to check conditions and charges for call forwarding with your mobile operator.

Alternatively, consider activating call forwarding to a virtual assistant provided by your mobile operator or third-party services. They will send you a message with a transcription of the call after the phone call is ended. Depending on your plan, these calls might be charged or spend the available time as outgoing calls.

Note: The app is entirely secure as it doesn't send your contacts or call numbers anywhere.
==How to get protected from phone spam?==

The most effective general advice to protect yourself from phone spam is still "Don't give your phone number to anyone, anywhere." However, in the era of digitization, it's practically impossible to avoid exposing your number. We provide it when attempting to obtain government or private services, for emergency contact, job searches, and so on. Data can leak from any online or offline organization, and even major companies experience such incidents.

So, approaching the issue of spam protection realistically, the only way to get protected is to use various call blockers. Based on their operation, they can be divided into two categories: 1. Those that block numbers listed in "black" lists (those marked as spam by someone), and 2. Blockers that allow only approved numbers.

KnownCalls belongs to the second type of call blockers, providing several advantages compared to those in the first category. KnownCalls doesn't require the Internet access to function, it doesn't share your data, and the blocking is performed precisely and instantly without delays, as there's no need to wait for a response from a database of spam numbers. Additionally, spammers often change numbers, so users of blockers in the first category (relying on spam databases) might be unlucky and fall victim to a "fresh" number that nobody has marked as spam yet.

Furthermore, KnownCalls is free and takes up little space. We recommend giving it a try! 

==Could you implement a feature which would disable the outgoing calls for the callers not from the contact list, as if the number didn’t exist? This would likely discourage them from calling back!==

You've installed the KnownCalls call blocker, and it has effectively saved you from receiving calls from unknown numbers. Great! However, while checking the app logs you've noticed that spammers have increased their calling attempts. While the calls themselves don't bother you, as KnownCalls rejects them, you’d like to understand why this is happening. Here's the explanation: the call frequency increase is unfortunately a common consequence. Spammers try to reach you, thinking you're using a typical program that only rejects calls from known spammers, hoping to get through with a number not yet blacklisted. Over time, they will give up their attempts when they realize they're facing more robust protection.

To reduce spammer calls even further, instead of call rejection, try contacting your mobile operator to set up call forwarding for rejected calls to a non-existing number. This way, the caller will hear a message stating that the number doesn't exist, and your number might be marked as unavailable, discouraging further attempts. Note: This feature is provided by your mobile operator, not us. Check your mobile operator’s details and conditions.

To activate this feature, dial *67+FullNumber# on your phone, where FullNumber is a non-existing international number (e.g., +71234567890). You'll need to find a non-existing number yourself. To deactivate the feature, dial ##67#. Ask your mobile operator for details and charges related to call forwarding.

We also recommend disabling voicemail to prevent blocked calls from being sent there.
==Why is KnownCalls only for Android?==

The KnownCalls app is designed exclusively for Android phones, as iPhones and iPads already have a built-in feature to block calls from non-contacts/favorites in the system settings. We'll provide more details about this soon in a separate post.

By the way, some Android devices also have a built-in feature to block "unknown" numbers, but unfortunately, it's not available for all devices. KnownCalls was created for Android phones and tablets lacking a straightforward call blocking option in their settings.

P.S. Additionally, KnownCalls is continually evolving and offers many more features than a simple standard call block, even on devices which has this feature embedded in the system settings. There's many more to come! So, even if your Android can block calls on its own, it's worth trying KnownCalls as our app is free and secure!

==How to Clear the KnownCalls Call Log?==

To remove an entry from the Call Log, tap and hold on it for a couple of seconds. You'll see a pop-up window with actions, where you can select "Delete."
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