A signaling protocol is essential for initiating, maintaining, and terminating real-time communication sessions. SIP plays a crucial role in real-time communication through calls, videos. This article explains the vital information about SIP. Let’s explore the details together.
What is SIP?
SIP refers to the Session Initiation Protocol that mainly sets up communication sessions over an IP network. SIP initiates and terminates an IP communication session, be it a voice call among two people or a video conference between a team. It sets up the session by sending messages (in the form of data packets) between two or more recognized IP endpoints, perceived as SIP addresses. Each SIP address is linked to a physical SIP client (i.e., an IP desk phone) or a software client (i.e., a softphone).
Let’s clearly understand how SIP actually works.
SIP is an application layer protocol that is the foundation of interactive conversation sessions over the internet. A protocol is defined as a set of commands that describe how two (or more) devices (laptops, phones, routers, and network switches, etc.) communicate.
Several protocols take place on the internet. For instance, when you make voice calls over the internet, several protocols are running together to make this possible. These various protocols form on top of each other in layers (this is a protocol stack). Protocol stacks may come in many shapes and sizes. The most obvious one to understand is the Open Systems Interconnection model, which consists of Application (SIP), Presentation, Session, Transport, Network, Datalink, etc.
The transport layer and the application layer of the protocol stack are the essential parts. The transport layer manages the agility, reliability, and order in which the data is being transferred. The data during a voice call is divided into packets and transported over the internet. The application layer defines the protocols that the software app requires to communicate over a SIP network connection.
A general mistake that people make is that SIP trunking presents all services of their communication sessions. But it does not. SIP session sets up a voice call, video calls, or any other form of the communication session and terminates it once it is completed.
There are five parts linked in the setting up and terminating of calls that SIP does. Here they are;
- Location – this informs the protocol where the end system is that it will be used for the call.
- Availability – this informs the protocol whether the called user is available to take the call.
- Capabilities – it is the determination of the media that will be used for the call.
- Set up – session setup includes the ringing from one user to the other.
- Management – session management involves running the communication session—for instance, the transfer and termination of the call.
How SIP Works During a Voice Call?
Voice information requires to be encoded with codecs before it is transmitted over the internet because the audio signals can be decoded into data. Encoded packages of audio data are transported, employing a real-time transport protocol (RTP), which has its own protocol application layer. This supports the transporting of audio and video data in real-time.
RTP control protocol operates with RTP to assure that the data about the RTP packet delivery is being used and the voice service quality is excellent.
Protocols then transport the RTP and the SIP packets at the transport layer. This can either be done utilizing a Transmission Control Protocol or User Datagram Protocol. User Datagram Protocol is more suitable for carrying Voice over Internet Protocol (VoIP) calls.
Besides, an application layer protocol works with SIP because it works as a media-independent application. This is recognized as the Session Description Protocol, and this signals what type of media the SIP client is sending the call and the client receiving the call can support.
In short, SIP has an important role to play for VoIP. From initiating the session to communicate in real-time, SIP protocols are required for IP communication. Now you have gained knowledge about SIP protocol and how it works. Why not determine if introducing SIP can help your business?