The non-profit Signal Foundation was launched in February 2018 with initial funding of $50 million from Brian Acton. The client software includes mechanisms by which users can independently verify the identity of their contacts and the integrity of the data channel. It secures all communications with end-to-end encryption. Signal uses mobile telephone numbers as identifier for users. Registration for desktop use requires an iOS or Android device. Signal is also distributed for iOS and desktop programs for Windows, macOS, and Linux. The official Android app generally uses the proprietary Google Play Services, although it is designed to work without them. Its mobile clients, desktop client and server are all published under the AGPL-3.0-only license. Signal's software is free and open-source. It is developed by the non-profit Signal Foundation and its subsidiary, Signal Messenger LLC. The application uses a centralized computing architecture, and is cross-platform software. Communication may be one-to-one between users, or for group messaging. The instant messaging function includes sending text, voice notes, images, videos, and other files. Signal is an encrypted messaging service for instant messaging, voice, and video calls. Encrypted voice calling, video calling and instant messaging

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