Whos Calling is a free Android app developed by P3 insight GmbH that reads the name of the calling party for incoming phone calls or the sender's name of a received message. It supports phone, SMS, WhatsApp and custom apps like Facebook Messenger. This app uses the default Text-To-Speech (TTS) engine and language pack. The user needs to ensure that "voice data" in TTS settings is installed.

The format of spoken caller ID is configurable, and certain contacts can be disabled or a custom name can be defined. The speech volume can be configured relative to ringtone volume, and it is possible to activate alerting only when connected to Bluetooth (R) hands-free. It has a test mode to simulate incoming calls and messages, and speech can be muted by flipping the phone. The app is designed to read notifications of enabled messaging apps without storing or sharing the information.