Do not call - Block Secretly is a free Android app developed by HBN Inc. It falls under the category of Utilities & Tools and offers users the ability to block unwanted calls. With this app, users can create their own blacklist of annoying and unwanted phone numbers, and all calls coming from those numbers will be automatically blocked.

The app provides two modes of call blocking. The Yellow mode blocks calls without anyone noticing that they are being ignored. This mode is recommended for calls from family, friends, or anyone who should not know that they are being blocked. On the other hand, the Red mode declines spam calls immediately. This mode is recommended for normal spam calls that are simply annoying.

Users can set a different mode for each caller according to their needs. Additionally, the app allows users to create a whitelist, where all calls are blocked except for those on the whitelist. The whitelist also has its own mode switch.

To function properly, the app requires permissions to access contacts in order to detect whether a number is saved on the user's phone, manage calls to detect phone numbers and callers, and access call logs to fetch the user's call history for blocking purposes.

With its customizable call blocking options and easy-to-use interface, Do not call - Block Secretly is a useful tool for those looking to block unwanted calls on their Android devices.