- VoIP SIP SDK for macOS – new product release October 27, 2017ABTO Software announces the release of VoIP SIP SDK for macOS (Mac OS X/ OS X) that allows you to quickly build a custom softphone app for Mac. The softphone suits needs of most users and provides the following functionality: – voice and video calls; – transfer calls; – calls recording; – IM; – secure connection via SRTP+TLS, ZRTP; – switching between multiple audio devices and ...