Signal app

Signal is a cross-platform centralized encrypted instant messaging service developed by the non-profit Signal Technology Foundation and Signal Messenger LLC. Users can send one-to-one and group messages, which can include files, voice notes, images and videos.[15] It can also be used to make one-to-one and group voice and video calls,[16][17] and the Android version can optionally function as an SMS app.[18] Signal uses standard cellular telephone numbers as identifiers and secures all communications to other Signal users with end-to-end encryption. The client software includes mechanisms by which users can independently verify the identity of their contacts and the integrity of the data channel.[18][19] Signal's software is free and open-source. https://en.wikipedia.org/wiki/Signal_(software)