Carrion

Automatically declines all calls failing STIR/SHAKEN verification.

What?

Ever receive a spam call and try to call it back, only for it to be out of service or some stranger? This blocks that.
STIR/SHAKEN provides cryptographic attestation of caller ID and is mandated by law in USA and Canada
https://www.fcc.gov/call-authentication
https://en.wikipedia.org/wiki/STIR/SHAKEN
https://fccprod.servicenowservices.com/rmd?id=rmd_listings

Install the app, grant the screening permission, nothing more!
A call that failed verification will be disallowed and a failure notification shown
A call that is unsigned will be allowed and a notification shown
- You can optionally choose to silence or block verification unsigned calls
A call that is verified will be allowed without any notification
Calls from contacts or emergency numbers are always allowed

For extra coverage and to enable functionality on devices without STIR/SHAKEN there is a local database lookup feature
Calls from numbers matched in the database will not be declined, but will be silenced
The archive database contains all numbers reported at least ten times in the past 360 data files
The high confidence database contains all numbers reported at least twice in the past 90 data files + the archive database
The "full" database contains all numbers reported in the past 30 data files + the high confidence database
You must manually download the database occasionally
The database function can be disabled via the delete database button
There is more information about the database here: https://www.ftc.gov/policy-notices/open-government/data-sets/do-not-call-data

VoLTE must be working
Your device must have official support for Android 11 or higher
If seemingly all received calls are unknown/unsigned state, your device/carrier is likely incompatible

Contacts permission is NOT required/used for exclusion
- The system itself will not pass calls from contacts to the active Call Screening app
The robocaller database is entirely optional, STIR/SHAKEN verification is completely independent
Internet is only optionally used to download the robocaller database
- Caller information, stats, and other information is never sent anywhere
The stats feature is entirely local for the user to observe effectiveness and is never sent anywhere
The archive database is included in both high and full database and cannot be used on its own
If you want to switch between databases and you just recently updated you must first delete the database
- This is because the app doesn't know which is actually saved and both databases likely have the same generation timestamp
The 'Excluded' stat counts outgoing calls to non-contacts, outgoing emergency calls, and all non-contact calls during emergency callback mode
Your carrier likely already does filter out calls that entirely fail verification
Your carrier likely does not filter out calls that are unsigned or partially signed

May fail to ask for screening permission, close the app and open until it prompts

Icons: Google/Android/AOSP, License: Apache 2.0, https://google.github.io/material-design-icons/