The Tox project is specifically designed to meet your usability requirements.
There were also forks of Signal which fixed the privacy issues, however Moxie Marlinspike (the founder of Open Whisper Systems) ordered them to cease and desist.
There were also forks of Signal which fixed the privacy issues, however Moxie Marlinspike (the founder of Open Whisper Systems) ordered them to cease and desist.
"Tox is by no means complete. You may encounter bugs ranging from simple visual defects to segfaults on file shares. We cannot guarantee what works today will work tomorrow; Tox is an alpha program and code changes daily. Certain commits may break existing APIs, and we strive to give proper advanced warning to all client developers, etc. when such changes will be made. Additionally, Tox has not yet received a full security audit. While we believe Tox is secure against attackers who want to decrypt your messages, you may wish to use a more established solution if you are in a life-or-death situation."
If you're in a life-or-death situation, I think you really ought to be doing some intensive research into secure communications to find the solution that will work best for you.
Would you be kind enough to provide links? I can't find any information about this claim via Google, and Signal is distributed under the GPLv3, which grants rights to fork and modify it: https://github.com/WhisperSystems/Signal-Android
tl;dr: You can fork the Signal code if you want, but if you do, Moxie Marlinspike asks you to change the app name and run your own servers. The server source code appears to be available at https://github.com/WhisperSystems/Signal-Server, but I've heard it doesn't include the voice component.
So, for example, if you think that Signal ought to support a feature like iMessage's "Invisible Ink" (https://mic.com/articles/146347/i-os-10-s-invisible-ink-feat...), which Moxie has specifically refused to support (https://github.com/WhisperSystems/Signal-Android/issues/5103), then you can't just fork the client, implement it yourself, and use the new client normally, because you'd no longer be able to talk to regular Signal client if I understand correctly. I mean, even if you figured out a way for two clients to tell each other whether or not the feature was available.
So Signal is open source, but not in a way that's useful if you want to change something.
I don't want to discourage people from using Signal. It's a great app. But I thought this was worth pointing out, assuming the LibreSignal is representative of what will happen if people want to make changes to their client.
Especially if the original client is under an open source license.