What Is SIP and Why Does it Matter?

By: Rahul Kumar on September 25, 2023
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SIP stands for "session initiation protocol” and enables voice, messaging, video, and other types of communication through application layer protocols. SIP was first developed by the Internet Engineering Task Force in 1996 to facilitate real-time communication sessions over the internet. In the late 1990s and early 2000s, internet usage was exploding, with 41% of adults going online for the first time in 1998. [1]

With the adoption and growth of the internet, there was a need for a standardized and flexible protocol that could enable various forms of communication over different IP networks. SIP was meant to establish easy communication regardless of the underlying technology or devices. In this article, we’ll discuss exactly what SIP is, how it works, how it differs from other communication protocols, and the benefits of using SIP in modern communications.

What is SIP, and how does it work?

SIP is the application layer protocol that initiates, maintains, and terminates IP-based calls. Protocols are a set of rules that define how two or more computing devices, such as laptops, smartphones, routers, network switches, and more, communicate with each other. SIP provides an overall common framework for communication sessions over the internet. SIP creates the modern foundation of interactive communications, like voice calls, video calls, and more.

How does SIP contribute to voice and video calls?

SIP is critical for the consistent standardization of different multimedia forms of communication over the internet. SIP is media-independent, meaning it’s not specifically for voice, video, or data; it simply could be any form of communication.

SIP contributes to voice and video calls by initiating and terminating an IP communication session. First, it establishes the session by sending messages in the form of data packets between two or more identified IP endpoints or SIP addresses. Every SIP address is linked to a physical SIP client like a phone desk or a software client like an application. SIP sends big chunks of text to initiate a session and request participation from another SIP client. Once the connection is established, other types of session protocols begin as well.

SIP is a core component of VoIP, the technology that allows you to make and receive calls over the internet. VoIP is an umbrella term for many different forms of voice communication that happen over the internet, and SIP describes exactly how these calls are established, maintained, and disconnected. SIP contributes to voice and video calls by being an underlying subprotocol of VoIP.

What are SIP addresses, and how are they used?

SIP addresses are similar to an email address that allows you to be identified by your real-time IP. SIP addresses are used to find a user's network location so communication can happen anywhere and anytime. SIP addresses are used to identify callers and their recipients. Similar to how a phone number is registered to a specific device, SIP addresses follow the individual users they belong to, and they are used to initiate and end the communication session.

Communication technology automatically detects SIP addresses and facilitates the communication. An end user would never need to keep track of an individual's SIP address.

How does SIP differ from other communication protocols?

SIP differs from other communication protocols in many ways. SIP has different goals, architecture, and functionality, especially compared to VoIP, WebRTC (Web Real-Time Communication), and SNMP (Simple Network Management Protocol). SIP VoIP systems are often compared to traditional physical landlines, but there are other communication technologies that SIP is very different from as well.

Zero data transportation

First, SIP does not decode, encode, or transport any information during these sessions. SIP simply tells you of the presence of another party, makes the connection, and then lets all parties continue communication however they want. It is not aware of what happens in conversations and is only responsible for the beginning and end. On the other hand, WebRTC transfers real-time audio, video, and data from device to device.

Supports multimedia

SIP supports different types of multimedia, like video and images, while a technology like VoIP only supports audio. Also, compared to a communication protocol like SNMP (Simple Network Management Protocol) that manages network devices and networking monitoring, SIP is more dynamic and supports different types of multimedia. As new types of multimedia, like virtual reality (VR), emerge, the underlying infrastructure of communication must be able to support these new advancements. 


Compared to traditional physical phone lines, SIP services are far more cost-effective. SIP providers typically charge 10% to 30% less than a traditional phone carrier. There is no need to pay for expensive hardware upfront or make regular annual upgrades for the latest version. Also, there is typically no long-term contract, so SIP technology is often more flexible. SIP technology is meant for dynamic changes, so as your business applications and integrations change, your communication protocols don’t become quickly outdated.


A core component of SIP is that it promotes interoperability between various systems and networks. With many different manufacturers and companies responsible for telecommunication, SIP is a common language. SIP is also flexible and versatile as it is used for a variety of both small-scale and large-scale communications. SIP was built with the goal of promoting collaboration and communication between all different types of users, and as the protocol has become more widely adopted, its original goal remains the same.

What are the benefits of using SIP in modern communication?

In modern communication, SIP makes dynamic, engaging communication happen in real-time. Without it, users would be relegated to simple audio communication. SIP facilitates high-quality audio and video, making rich communication happen in real-time all over the globe. It also supports features like screen sharing and file transfers during these communication sessions. 

Without SIP technology, modern communication would look incredibly different; remote work would be much more difficult, global communication would be riddled with technology glitches, and businesses would be more vulnerable to cyberattacks.

Facilitates remote work

For businesses, SIP makes engaging communication with investors, partners, customers, and clients possible. As a majority of workers work remotely at least one day a week, SIP makes secure, geographically distributed communication possible. Employees can enjoy the same communication tools they would use if they were in the office.

Reduces communication barriers

For modern businesses, communication is truly a global endeavor. Companies need to communicate with different partners in vastly large areas around the globe. No matter the underlying information technology, SIP enables people in different countries with different communication devices and platforms to interact seamlessly.

Improves disaster recovery

All businesses need to be wary of cyber attacks, with nearly 60% of small to medium-sized businesses experiencing a cyber incident within the last 12 months. [2] SIP also supports redundancy and provides failover mechanisms, ensuring that communications can still happen during a cyber incident or network disruption.

Encourages future-proofing

SIP also provides businesses and communication technology with a layer of future-proofing. It can easily incorporate new features and protocols as communication needs change. Small businesses, especially, can quickly adopt new communication tools and technologies, allowing them to stay ahead of the curve and competitive. Having a flexible, scalable underlying infrastructure helps them adapt to changes quickly.

Choose a SIP provider

For your business, choosing a SIP provider is an important part of your information technology strategy. There are a few things to consider before choosing a provider.

Understand your business needs

First, assess your business needs and determine your true communication requirements, such as call volume, the different types of communication, and the number of users. Also, as your business grows and scales, your needs might change, so look for a flexible provider that is willing to grow with you.

Look for a solid reputation

Look for SIP providers with high availability and redundancy to ensure minimal downtime. Plus, double-check provider online reviews and testimonials to research customer experience. Talk with other business owners in your industry to learn more about their SIP providers, too.

Compare features

Depending on your business and industry, you might need specific features like extensive integration options, video conferencing, call forwarding, and more. You don’t need the provider with the greatest number of features, just the ones that are pertinent to your business.

Assess compatibility

Work with internal IT teams to assess your compatibility needs. Ideally, you want to avoid paying for redundant systems, and working closely with your IT team will help you stay within budget.

Next steps to finding the right SIP provider for your business

At Software Advice, we specialize in helping business owners like you assess software features and products and help you make the right decision for your budget, goals, and needs. We provide free, fast, personalized software recommendations, so schedule an appointment with an expert software advisor here.

For even more resources on SIP and other vendor implementation, check out the articles below: