baresip+

Baresip+ is security focused open source communication app that originally only supported SIP based voice and video calling and messaging. Now baresip+ can also be chosen as Android's default mobile calling and messaging app. In addition, contacts are integrated within the app. Voice conference calls, voicemail indication as well as blind and attended call transfers are available when VoIP is used. In SIP calls audio can be coded with AMR, Codec2, G.729, G.722, G.722.1, iLBC, opus or PCMU/PCMA codecs. Video can be coded with VP9, VP8, H.265, H.264, or AV1 codecs. Security is achieved via TLS or WSS SIP signaling transport and ZRTP or (DTLS) SRTP media encapsulation. Baresip+ app can be installed on Android devices running Android version 9 or later. Mobile calling and messaging needs Android version 10 or later. If you don't need video calls, you can instead of this app install its lighter weight sister app baresip. Source code is available at GitHub, where also issues can be reported.