Block incoming calls. How to extract offline database from Whoscall

Prepare apk and root phone

Download apk of gogolook whoscall from some website like this.

Install apk to a rooted android phone, I recommend samsung i9001.

A little bit old, but great performance running CyanogenMod. Here's how you can root your i9001

Download offline database

Update offline database following instructions in Whocall app, this will create a database named

Under android /data/data//databases/offline.realm

Use Android studio device monitor tools to navigate to above path,

Click the button (top-right) to "pull file from device"

Save it to your Download folder on your laptop, say whoscall_database

.realm is a client-side database that helps you seamless integrate a sqlitedb and scale-up if needed. Realm database help manage db when gets larger.

https://realm.io/products/realm-database

Download real browser from above site to your Mac laptop

Open Download/whoscall_database/offlinedb.realm

I'm using a Taiwan number so most of the database are numbers in Taiwan.

Looks like when a call comes in, whoscall is using a hash function to calculate from the phonenumber to a hash value and then search from the offline database for a hit. If so, shows a warning triangle on the lock screen.