5 minute read |

What is the Difference Between VoIP and SIP?

VoIP phone service background

In the enterprise world, practically every technology comes with an avalanche of acronyms. Take telephony for instance. Not many people know what exactly PSTN, PRI, ISDN, VoIP, SIP, etc. mean. Sure, you may have a vague idea that it is used somewhere in the office. But few people have a better idea than that. 

So it’s not surprising that one of the most commonly asked questions is – what’s the difference between VoIP and SIP? To an industry expert, the difference is glaringly obvious. For aamateur, not so much. It often seems that vendors use them interchangeably but they also refer to different things.  

Before you decide on a particular system for your business, take a few moments to understand the terms VoIP and SIP. 

VoIP vs. SIP 

When people ask about the difference between VoIP and SIP, they usually want to know which one to use. What is better for their company? Unfortunately, comparing VoIP and SIP is ineffective. That’s because they’re referring to completely different things. 

What Is VoIP? 

VoIP stands for Voice over Internet Protocol. In short, it refers to any technology that allows voice signals to travel over the Internet. It can also be called broadband telephony, Internet telephony, and many other names. It doesn’t matter what technology you use or the hardware and software. Remember that if a voice call travels over the Internet, it can be called VoIP. 

What Is SIP? 

SIP stands for Session Initiation Protocol. A protocol is a system of digital rules that allows devices to talk to one another. Think of it as a language for computer hardware. If your computer and modem don’t speak the same language, they cannot communicate.  

SIP is simply one of many protocols that can be used to implement VoIP. It is used to set up and terminate multimedia sessions, including voice and video. At present, it is the most widely used protocol and is the industry standard. Perhaps when users are trying to figure out what VoIP is, the industry standard of using SIP with VoIP is why many people get confused between the two. SIP is almost ubiquitous in the industry. 

The Relationship Between VoIP and SIP 

Now that you know the specifics of what VoIP is and what SIP is, it’s time to understand how they relate to one another. It is similar to the relationship between websites and HTML. A website is a collection of pages that is accessible with a web browser. HTML is one language that you can use to build websites. However, most websites also use other languages such as Java. 

Similarly, VoIP refers to any method of sending voice calls over the Internet. That means everything from Skype and FaceTime to enterprise phone services fall under the same umbrella. SIP is just one of the many protocols currently in use. So, you can implement VoIP with other protocols as well.  

For example, Skype does not use SIP. But most enterprise-level phone systems rely on it. In other words, not every VoIP system will use SIP. But the vast majority of VoIP services do utilize it since it is the industry standard. 

VoIP Only or VoIP With SIP 

It’s not entirely helpful to compare VoIP to SIP directly, it’s more useful to list the pros and cons of VoIP with and without SIP. 

If you only need voice communication, you may opt to not use SIP. It requires little to no investment, with ongoing cost savings. These systems don’t require on-site installation and are very portable. You can get basic features like caller ID and call waiting. 

There is a reason why most organizations prefer to use VoIP with SIP. In fact, there are several. The first thing is that you can integrate different types of multimedia channels into a single system. You can transmit voice calls, video calls, conference calls, etc. It can integrate seamlessly with unified communication (UC) suites. It is very flexible and provides failover options in case of emergencies. 

Sooner or later, organizations find that they have to upgrade to VoIP with SIP for advanced features. Keeping in mind future growth and expansion, it’s no wonder that the latter option is more popular. 

Why is SIP Important? 

A protocol is a system of rules for exchanging messages between hardware. Modern digital services use many protocols such as SIP, TCP, HTTP, etc. A protocol defines the syntax and semantics of communication. For a protocol to be useful, different vendors must agree to use it on devices and applications. Over time, many protocols evolve to become industry standards as the vast majority of developers start using it. 

SIP is one such industry-standard used in VoIP. SIP dictates how messages are sent between endpoints to set up and manage multimedia sessions. The actual voice and video are carried by other protocols. SIP handles the management portion of calls. Most organizations opt for SIP as they can be sure of interoperability. You can buy SIP compatible hardware and know that it will work with your system. You don’t have to worry about compatibility and integration issues. 

Types of VoIP Deployment 

There are different types of VoIP deployment that one could use for their business.  When choosing the right services for your communication needs, you should consider all types of deployment to ensure you make the best decision for you and your business.  Some of the most popular VoIP deployments are as follows:

Hosted VoIP 

When most people think of VoIP, they are imagining a hosted service. In this type of deployment, the vendor manages the PBX and all associated components. Phone services are delivered over the Internet to clients.  

Hosted services are popular because it removes the hassle of maintenance and repair. You don’t have to manage the system, buy expensive hardware or update it periodically. It is quick and easy to start using hosted VoIP services. 

There are cons to this type of deployment. You don’t have any control over security, customization, feature upgrades, etc. You have to trust your vendor to take care of their infrastructure. While hosted services can cut your monthly telephone bills, the costs can add up over time. 

SIP Trunking 

SIP trunking is a method of delivering phone services to enterprises with their own IP PBX. It replaces the standard PRI line between organizations and traditional phone carriers. It serves as a bridge between VoIP and the public phone network (PSTN). A SIP trunk is not a physical line but a virtual connection between your business and ITSP (Internet Telephony Service Provider). 

The vendor is only responsible for the connection and providing a dial tone for you to use. You have to manage the PBX yourself. That means your team decides what features to enable and manage. You control when and how you upgrade your hardware and software. You are responsible for data security and privacy. 

SIP trunking is more expensive to set up than hosted services. However, it can save a lot more money for organizations with high call volume. In other words, SIP trunking gives a better return on investment than hosted services. 

Which One Should You Choose? 

Most VoIP hosted services use SIP as the protocol of choice. So whichever type of deployment you choose, SIP will be a major component. Now we can ask the more relevant question rather than, what is VoIP? Should you go for hosted VoIP services or SIP trunking? 

As with most technology-related questions, the answer is – it depends. It depends on a number of factors including: 

  • Your business needs and requirements 
  • Your budget and resources 
  • Availability of in-house expertise 
  • Long-term considerations 

Business Needs 

One of the primary differences between hosted services and SIP trunking is control. In the former option, you have very little control over features, customization, security, etc. With SIP trunking, you’re in charge of everything.  

There are hundreds of VoIP services in the market today. So most businesses will be able to find a vendor that meets their requirements. But if a hosted service cannot meet your business needs, then SIP trunking is the obvious choice. 


While SIP trunking it is definitely cheaper in the long-term, you do need the money to invest upfront. You have to purchase the IP PBX and other hardware components. For many small and medium businesses, the initial outlay may be well out of their reach. On the other hand, you can get started with hosted VoIP services for as little as $25 per month per user. 

In-House Expertise 

With hosted services, you don’t need a team to manage the phone system. The vendor handles everything. A reputable provider will have multiple resources for troubleshooting and support as well. With SIP trunks, you need to have a team that can deploy and maintain the phone system. If you already have a team in place, that’s great. If not, you might have to hire more people which can get expensive.  

Long-Term Considerations 

What is the growth potential for your business? How much change do you anticipate over the long-term? Hosted VoIP services can scale quickly. But if your business needs change dramatically, your current provider may not be able to meet them. 

Expanding your SIP trunking installation may require further investment. But for a large or growing business, it makes sense to retain control over the phone systems. The longer you use it, the lower your costs per user or per line. 

Now that you know the pros and cons of VoIP deployments, it’s easier to decide. Consider your business requirements, budget, and other factors before committing to either hosted VoIP or SIP trunking solutions. 

If you have any further questions about what VoIP is or the benefits of using SIP with your VoIP system, contact us and we would be happy to help! 


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