Voice

Here are some open source options for secure audio communication over the internet, along with some details about their security:

Signal: Signal is a free and open-source messaging app that offers end-to-end encryption for voice and video calls. End-to-end encryption ensures that only the sender and the recipient of a message can read its contents, and not even the service provider can access it. Signal’s encryption is based on the Signal Protocol, which is considered to be highly secure and has been adopted by other messaging apps such as WhatsApp and Skype.
Jitsi Meet: Jitsi Meet is a free and open-source video conferencing solution that offers end-to-end encryption for audio and video calls. Jitsi Meet uses the WebRTC standard for real-time communication, which provides encryption for both media streams and signaling. Jitsi Meet also offers additional security features such as password-protected rooms and the ability to lock a room once everyone has joined.
Linphone: Linphone is an open-source VoIP and video conferencing application that offers end-to-end encryption for audio and video calls. Linphone uses the ZRTP encryption protocol, which provides strong security without requiring users to manually exchange keys. Linphone also supports secure communication over IPv6, which can help to mitigate some network-level attacks.
Mumble: Mumble is an open-source, low-latency, high-quality voice chat software primarily intended for use while gaming. Mumble offers end-to-end encryption for voice calls, which is based on the OCB-AES128 encryption algorithm. Mumble also provides additional security features such as channel-specific permissions and user authentication based on digital certificates.

These open-source options are generally considered to be secure because their source code is available for review by security experts and developers around the world, which helps to identify and address potential vulnerabilities. Additionally, many of these solutions use well-established and trusted encryption protocols to protect communications, and some offer additional security features such as password protection and user authentication. However, it’s important to note that the security of any communication tool depends on its specific implementation and configuration, so it’s always a good idea to carefully review and understand the security features of any tool before using it to discuss sensitive information.