PJSIP is open source SIP, Media and NAT traversal library (www.pjsip.org)
This is a prebuild pjsip library included universal libraries for armv7, armv7s, arm64, iPhoneSimulator
This fork supports SSL.
The best way is using cocoapods.
Check the Podfile configuration:
platform :ios, '5.1.1'
pod 'pjsip', :path => '~/path/to/this/checkout'
and run pod install
git submodule init
git submodule update # for ios-openssl
./build.sh # (starts fresh)