Currently this baresip app supports SIP voice calls and messages with
TLS transport, voicemail Message Waiting Indication (MWI), incoming call
transfers via REFER method, PCMU/PCMA and opus voice codecs, as well as
ZRTP and (DTLS) SRTP media encapsulation.

Development of this baresip app is motivated by need for a secure open
source SIP User Agent for Android that does not depend on proprietary,
third party push notification services.

Source code is available at https://github.com/juha-h/baresip-studio.