belle-sip : SIP (RFC3261) implementation written in C, with an object oriented API ( http://www.linphone.org/technical-corner/belle-sip/overview )
libeXosip : library that hides the complexity of using the SIP protocol for multimedia session establishement ( http://savannah.nongnu.org/projects/exosip/ )
libosip : a simple way to support the Session Initiation Protocol ( http://www.gnu.org/software/osip/ )
mbedtls : Cryptographic library for embedded systems ( https://tls.mbed.org/ )
ortp : Open Real-time Transport Protocol (RTP, RFC3550) stack ( http://www.linphone.org/ )
polarssl : Cryptographic library for embedded systems ( http://polarssl.org/ )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a prism-overlay
For Paludis use this rsync : rsync://gentoo.zugaina.org/prism-overlay-portage
If you have a problem : ycarus(-at-)zugaina.org