VoIP SIP SDK for iOS (iPhone and iPad) is a toolkit to quickly build SIP softphone client for iOS or add VoIP features into your app for App Store.
Mac OS X.
VOIP SIP SDK for iPhone on objective-C (Xcode);
VOIP SIP SDK for iPhone on Swift.
VoIP SIP SDK for iOS 6;
VoIP SIP SDK for iOS 7;
VoIP SIP SDK for iOS 8.
supports 64 bit architecture;
STUN and other IETF standards (compatible with SER, OpenSER and Asterisk);
SIP Registrar (SIP server) - including Asterisk and ABTO Software SIP Server;
voice and video calls;
work in background mode;
phone contacts book support;
secure connection via SRTP and ZRTP;
changing camera orientation;
switching between multiple cameras.