SIP is a text-based, application-Layer control signaling protocol that is used for setting up, modifying and tearing down multimedia sessions between participants and takes advantages of elements of HTPP, SMTP and SDP.
SIP Protocol can use TCP or UDP at the transport layer. The port used is then TCP/UDP/5060 but is TCP/5061 for TLS over TCP
It can use as well multicast as well unicast communication or a combination of the both.