#Sip definition telecom drivers#

The call setup part of the process involves organizing the details that get two phones or devices to connect. The enterprise SIP server determines the SIP endpoint that users will communicate with, except in the case of SIP phones, which connect directly to the service provider. Then, SIP establishes call parameters at either end of the communication, also handling call transfer and termination.

SIP determines the endpoint used for a session, the communication media and media parameters, and whether the called party agrees to communicate. The proxy acts as an intermediary system to offload tasks that would otherwise be handled by SIP. Requests can be sent through any transport protocol, such as User Datagram Protocol, Stream Control Transmission Protocol or Transmission Control Protocol.ĭevices using SIP communicate with each other directly via a SIP proxy server. SIP receives requests from clients and responses from servers. Requests and responses are the names message protocols send between devices to communicate. This makes SIP easier to read and debug compared with similar signaling protocols, like H.323. SDP is used to describe multimedia communication to sessions for invitations, announcements and parameter negotiations.Īlso, SIP is a text-based protocol, like HTTP, which means its content is in a readable format. SIP will also work in tandem with other protocols, namely Session Description Protocol ( SDP), which is contained in SIP messages. SIP can be thought of as a client-server architecture. Like HTTP or SMTP, SIP works in the application layer of the Open Systems Interconnection communications model. SIP operates similarly to, and incorporates parts of, Hypertext Transfer Protocol ( HTTP) and Simple Mail Transfer Protocol ( SMTP). SIP allows proxy servers to communicate so that, afterwards, users can communicate using Real-time Transport Protocol. In addition to real-time services, SIP is used for asynchronous event notifications, such as automatic callbacks, message-waiting indicators and buddy lists based on presence. Other SIP features are available through application programming interfaces. URIs are alphanumeric, using a syntax that looks more like an email address than a phone number or IP address. Users and endpoints are detected with a single identifier, or Uniform Resource Identifier ( URI), which is independent of their network location. SIP also supports name mapping and redirection services, which are two ways the protocol enables mobility.

Primitives enable additional information to be embedded in a SIP message, such as linking a user's photo to directory information to enhance the user's caller ID. Instead, it defines interoperable implementations of SIP features, called primitives, which are used to facilitate different services. SIP does not provide communication services. The protocol can be used to invite participants to unicast or multicast sessions that do not necessarily involve the initiator. SIP sessions can include internet telephony, video conferencing and other forms of unified communications. The SIP communications protocol determines five attributes when establishing and terminating multimedia sessions:

SIP complements other communications protocols, such as Real-Time Transport Protocol ( RTP) and Real-Time Streaming Protocol, used in IP-based sessions.

#Sip definition telecom drivers#

Native support for mobility, interoperability and multimedia was among the drivers behind SIP development. SIP addresses the evolving needs of IP-based communications. SIP was developed by the Internet Engineering Task Force in 1996 and standardized in 1999. SIP enables voice, messaging, video and other communications applications and services between two or more endpoints on IP networks. Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, modifying and terminating real-time communications sessions between Internet Protocol ( IP) devices.

What is Session Initiation Protocol (SIP)?