Apps Related to Voice Call

QuteCom, formerly WengoPhone, was a free and open-source VoIP client supporting the SIP protocol. It enabled users to make voice and video calls, send instant messages, and connect with contacts across various networks, including Google Talk.

Psi+ is a robust, cross-platform XMPP/Jabber client tailored for users who prioritize control, privacy, and extensibility. As a development branch of the classic Psi client, it offers advanced features for secure and customizable instant messaging.

qutIM is a free and open-source, multi-protocol instant messenger designed for connecting to various networks including ICQ, Jabber, Mail.Ru, IRC, and VKontakte. It offers a unified interface for managing multiple accounts and conversations.

Ekiga, formerly known as GnomeMeeting, is a free and open-source VoIP and video conferencing application. It allows users to make audio and video calls to other compatible SIP/H.323 clients and even landlines/mobile phones via integrated third-party services, offering a versatile communication solution.

Ring (SFLphone) is a free and open-source communication platform offering secure messaging, voice, and video calls. It leverages decentralization and end-to-end encryption for enhanced privacy across multiple operating systems including Linux, Windows, macOS, and Android.

Mattermost is an open-source, self-hosted platform for secure team collaboration, offering a Slack-alternative with emphasis on data control, privacy, and customizability. It provides a range of communication and project management tools for distributed and technical teams.

Linphone is a free and open-source Voice over IP (VoIP) application and SIP client available on multiple platforms. It enables encrypted voice and video calls, instant messaging, and file sharing, offering a privacy-focused communication solution.

Empathy is a versatile multi-protocol messaging client designed for text, voice, and video communication across numerous IM networks. It offers features like file transfers, location sharing, and integration with various services, providing a unified communication experience.

Digsby was a multi-protocol instant messaging client that unified connections to various chat networks and social media platforms. It allowed users to manage their conversations and updates from services like Aim, Msn, Yahoo, Twitter, Facebook, and Myspace all within a single, integrated application.

Tox is a free, open-source, and secure peer-to-peer instant messaging and video calling protocol designed for strong privacy and censorship resistance. It provides end-to-end encrypted communications without reliance on central servers.

Matrix is an open network for secure, decentralized real-time communication. It provides a flexible protocol for developers to build collaborative applications like instant messaging, VoIP, and video conferencing, enabling seamless communication across different service providers.