Linphone - open source SIP client

Téléphone SIP (VOIP)GPL-3.0-only

Sipdroid

Un client SIP (VOIP)GPL-3.0-only

baresip

SIP and mobile calling and messaging User Agent for Android based on baresip libBSD-3-Clause

baresip+

SIP and mobile calling and messaging User Agent for Android based on baresip libBSD-3-Clause

Jami

Share, freely and privatelyGPL-3.0-or-later

Nextcloud Talk

Have private video calls and chat using your own server.GPL-3.0-only