
Wazo.io
Asterisk
FreeSWITCH
FusionPBX
Kamailio
miniSIPServer
XiVO
VoipSwitch
Mobile Node
Sipdroid
Zoiper
MicroSIP
Fongo
Linphone
MizuDroid
Sipnetic
Mobile NodeAsterisk - An open source telephony switching and private branch exchange service for Linux.
Sipdroid - Free and open-source SIP/VoIP Client
FreeSWITCH - FreeSWITCH is an open-source media application designed to support popular protools such as SIP and WebRTC and provides a platform to develop voice and video applications.
Zoiper - Cross-platform VoIP softphone dialer for SIP and IAX systems
FusionPBX - FusionPBX is an open source FreeSWITCH GUI.
MicroSIP - MicroSIP is a free portable SIP softphone for Windows based on PJSIP stack.