SIP clients traditionally use port 5060 TCP and UDP voip italy connections to servers and other elements of the SIP. SIP is primarily used for establishing and tearing down voice or video calls voip israel. Thus it can be used in any other applications that require installation of connections, such as the Event Subscription and Notification, Terminal mobility and so on. There are a large number of RFC, related to the SIP and determine the behavior of such applications voip russia. To send themselves voice and video using other transport protocols, most Real-time Transport Protocol (RTP).

The main goal for SIP VoIP Czech Republic was to create a signaling protocol and the protocol connectivity for IP-based communications that can support a superset of the call processing functions and services provided in the existing PSTN VoIP Belgium. SIP by itself does not define these functions, but focuses only on the call-setup and signaling. It was designed to ensure the creation of such functions of network elements, as a proxy server (Proxy Servers) and User Agents (User Agents). With these elements can maintain basic telephone operations: dialing, call the telephone, the ability to hear after dialing a long or short beeps.