VoIP vs SIP - What's the Difference?

Updated: December 20th, 2023

VoIP vs SIP – Everything You Need to Know


VoIP vs SIP - What's the Difference?


When it comes to internet-based telephony, the acronyms SIP and VoIP appear frequently. If you are making the move away from legacy, PSTN-reliant solutions to internet-based telephony, you will have come across both of these terms and may be wondering what the difference is between them. Both technologies enable you to place and receive calls via the internet, but the way in which these technologies work and their role within internet telephony are vastly different.



Having a clear idea of what these technologies are, how they work and the key differences between them is important in order to choose the best internet-based telephony solutions before the PSTN switch off in 2025. Don’t worry, we’re here to help! We’re going to break down these technologies, so by the the end of this article, you are fully clued up on what they are; to help you make an informed decision on the best phone system for your business.


Why is VoIP Commonly Confused with SIP?


The first, obvious reason why VoIP is confused with SIP is because they’re both acronyms, containing the letters I and P and relate to internet-based communications. Another reason, is the fact that although these terms have two completely different technical meanings, many people use them interchangeably. Naturally, both of these factors cause a suitable amount of confusion, which isn’t helpful for people who are trying to research internet-based telephony in order to make a decision on a business phone system.


If you are one of these people who whisper: “I just want to know which I need to buy for my business”, despairingly into your laptop screen – we feel your pain and we’re going to make this simple for you.


What is VoIP?



VoIP stands for Voice over Internet Protocol. Traditional telephony relies on a legacy network of copper lines known as the PSTN. This network will be decommissioned by 2025, as it doesn’t support the communication needs of the modern world. We’ve moved on from simple telephone calls in favour of implementing a range of communication channels, including conference calling, video calls, instant messaging and more – the PSTN just isn’t designed to support this whereas VoIP is.


Even though the deadline for the PSTN switch off is 2025, this doesn’t mean that businesses can delay moving over to VoIP before then – decommissioning has already begun – the 2025 date is a deadline for completion. Businesses who don’t move across from PSTN-reliant telephony to VoIP telephony risk having their phone system made obsolete, as it will no longer be connected to a network, causing expensive disruption and downtime until a new VoIP solution is sourced.


How Does VoIP Calling Work?


This technology enables phone calls over the internet through packet switching technology to transmit audio signals. When a VoIP call is placed, the VoIP network connects your VoIP device, such as a desk phone, laptop or mobile to a carrier network. The VoIP device then converts the audio signal into data packets before the packets are transmitted over the internet network and turned back into sound at the other end.


Read More: Is Your Internet Connection Good Enough to Deliver VoIP?


What is SIP?


Session Initiation Protocol (SIP) is an application protocol that facilitates VoIP telephony. In short, it’s the technology that can start, maintain and terminate multimedia communication within VoIP applications that allow business phone systems to integrate voice, video, fax and messaging for multi-channel communication channels.


How Does SIP Work?



SIP facilitates VoIP communications by allowing your business phone system to run over the internet rather than analogue telephone lines. In addition to transferring voice data, SIP enables file sharing, instant messaging, video conferencing and other multimedia sessions. SIP is utilised within SIP trunking, which enables businesses to connect their phone system to the internet to move over to VoIP communication.


Read more: What Do You Need to Do to Make the Move From ISDN to SIP


What is the Difference Between VoIP and SIP?


Ok, so we’ve covered what VoIP and SIP is, but let’s really pinpoint what the difference is between the two technologies. The difference between VoIP and SIP is:


VoIP: umbrella term for calls placed via the internet.


SIP: a technology that can enable VoIP calls by connecting your business phone system to the internet.


All calls placed via the internet are VoIP calls, but not all VoIP calls are supported by SIP technology. SIP is just one protocol that can be used to facilitate VoIP communication, but it is the most used protocol to enable VoIP.


What Do I Search for SIP and VoIP Solutions?


Knowing whether you should be scrolling through Google for information on SIP or VoIP depends on your intent for the search. If you are still relying on a PSTN-reliant service and are assessing your options to move across to internet-based telephony, we would recommend that you read up on SIP, specifically SIP trunk solutions. This is the technology that will hook your business phone system up to the internet to allow you to take advantage of a VoIP solution. SIP trunks are a really valuable and commonly-used solution to move legacy communication systems across to the internet, but they’re not the only solution that can achieve this. Check out our Hosted PBX vs SIP trunks to explore two common methods to move your phone system online.


Alternatively, if you know how you are going to make the move to VoIP communications (i.e. via SIP trunking, hosted PBX or another solution), we would recommend researching VoIP business phone systems and VoIP providers to outline the platform you are going to use to access and manage your phone system and the provider that supply the network. We would recommend reaching out to a knowledgeable provider, like Elite Group, to access specialist advice and support, so you have full understanding of the solutions available to you and which are best for your business.


Read more: This Isn’t SIP Trunks For Dummies, It’s SIP Trunks For Everyone


Enable VoIP with the Right Solution from Elite


With over 20 years of experience in the telecommunications industry, Elite have the expertise and technical skills to enable VoIP solutions with the right SIP solution. When you work with Elite, there’s no need to shop around for multiple solutions, we can source and install both your SIP and VoIP solutions within one easy contract with us. Ready to make the move to VoIP with SIP? Contact us or call us on 0344 875 8880