Call Blocker Not Working on Android? 8 Things to Check
Most failures come from the Android call-screening role or an exception that is working as configured. Walk through this checklist in order before reinstalling anything.
1. Confirm the Android call-screening role
Android binds incoming calls to the single user-selected app holding the call-screening role. If another app has the role—or no app does—Block Unknown Callers cannot filter calls. Open the app and accept the system prompt again if needed.
2. Check the selected mode
Off allows all calls. Silence mutes non-contacts but does not reject them. Choose Block when you expect the call to be declined.
3. Check whether filtering is paused
A temporary pause intentionally lets calls through for 30 minutes, 1 hour, 3 hours, or the rest of the day. End the pause before testing.
4. Review the allow list
An exact-number or prefix allow-list rule overrides blocking. A broad prefix can allow more numbers than expected, so test after disabling suspicious rules.
5. Review repeat-call bypass
The same displayed number may be allowed after repeated calls within the configured window. Disable the bypass temporarily when diagnosing.
6. Check whether the caller is saved
The main rule allows saved contacts by design. If you want to block one specific saved person, use the Phone app's per-number block feature.
7. Check filter scope
If the scope is set to International numbers, domestic non-contact calls are allowed. Choose All to handle all numbers outside Contacts.
8. Test correctly and separate voicemail from ringing
Test from a visible unsaved number on an Android 10+ phone. Then check Blocked & Silenced History. A rejected call may still reach carrier voicemail, which does not necessarily mean the device blocker failed.
Still not working?
Record the phone model, Android version, app version, selected mode, scope, and whether the test caller was saved. These details make support diagnosis much faster.
Official Android reference
Android documents that Telecom binds to one user-chosen app filling ROLE_CALL_SCREENING, and that the service can allow, silence, or disallow an incoming call. See CallScreeningService.
For a plain-language explanation, read what Android call screening is.
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Frequently asked questions
Why is my call blocker allowing every call?
First confirm that it holds Android's call-screening role and that the selected mode is Block rather than Off or Silence.
Why was one unknown number allowed?
Pause, an allow-list rule, repeat-call bypass, a saved contact, or international-only scope may have allowed it.
Can two call-screening apps work at the same time?
Android binds screening to a single user-selected app holding the call-screening role, so choose the app you want active.
Why do I get no blocked-call notification?
Blocking and notifications are separate. Check Android notification permission and system notification settings.
Does voicemail mean blocking failed?
Not necessarily. The carrier may route a rejected call to voicemail even though the phone never rang.