This is a bare-bones <a href="https://github.com/alfredh/baresip">baresip</a> based SIP User Agent application for Android.

Currently the application supports voice calling and messaging, UDP, TCP, and TLS signaling transports, voicemail Message Waiting Indication, incoming call transfers (REFER), PCMU/PCMA, iLBC, G.726, G.722, G.722.1, AMR, and Opus voice codecs, as well as ZRTP and (DTLS) SRTP media encapsulation.

Motivated by need for a secure SIP user agent for Android that does not depend on third party push notification services.