Jitsi

Pidgin - бесплатная программа для мгновенного обмена сообщениями. Сохраняет переписку между контактами, позволяет сортировать контакты по группам, создавать чаты/конференции. Доступны установка аватаров, обмен файлами, изменение шрифта, смайлы, метаконтакты и многое …

Adium is a free and open source instant messaging application for Mac OS X, written using Mac OS Xs Cocoa API, released under the GNU GPL and developed by the …

Empathy is a messaging program which supports text, voice, and video chat and file transfers over many different protocols. You can tell it about your accounts on all those services …

Ekiga (formely known as GnomeMeeting) is an open source VoIP and video conferencing application for GNOME. Ekiga uses both the H.323 and SIP protocols. It supports many audio and video …

Linphone is an internet phone or Voice Over IP phone (VoIP). With linphone you can communicate freely with people over the internet, with voice, video, and text instant messaging. Linphone …

csipsimple will allow native sip for android device. It relies on the pjsip SIP stack and use the pjsip-jni project. The use of this native library will ensure a better …

Psi+ is a development branch of Psi IM XMPP/Jabber client. Psi is a cross-platform powerful XMPP/Jabber client (Qt, C++) designed for the Jabber power users.

QuteCom is a community of enthusiasts and developers, creating free software products related to communication over IP. The flagship product of the QuteCom project is a softphone which allows you …

SFLphone is a robust standards-compliant enterprise softphone, for desktop and embedded systems. It is designed to handle several hundreds of calls a day. SFLphone is available under the GNU GPL …

Telephone is a VoIP program which allows you to make phone calls over the internet. It can be used to call regular phones via any appropriate SIP provider, including Google …

Encrypted voice for Android. RedPhone provides end-to-end encryption for your calls, securing your conversations so that nobody can listen in. It's easy to use, and functions just like the normal …

MicroSIP - это портативный программный телефон SIP на основе стека PJSIP, доступного для Microsoft Windows. Он обеспечивает высокое качество вызовов VoIP на основе открытого протокола SIP.

An IRC client for the Windows desktop which follows the Metro design guidelines.

WengoPhone is an open source phone software. You can talk for free to other Wengo users, and phone landline at cheap rates.

Crossplatform Jabber client. The core program is just a plugin loader - all functionality is made available via plugins. This enforces modularity and ensures well defined component interaction via interfaces.

Subway is a web-based IRC client with a multi-user backend and a JavaScript-heavy UI. Frontend/backend communication is done with websockets (or best available fallback where not available). The backend...

Twinkle is a soft phone for your voice over IP communcations using the SIP protocol. You can use it for direct IP phone to IP phone communication or in a …