Skip to main content


SIP trunking vs VoIP – What’s the Difference?

Katlyn Edwards Katlyn Edwards
Katlyn Edwards

As much as the telecom industry tries to make things simple for the masses (heavy sarcasm), this one seems to have slipped through the gaps.

At a quick glance here’s what you need to know:

  • IP – Internet Protocol
  • VoIP – Voice Over Internet Protocol
  • SIP – Session Initiation Protocol
  • Trunking – Grouping

Still confused? Well thankfully, we consider ourselves IP trunking and SIP trunking experts, so let us go through the difference.

What is SIP trunking vs VoIP?

Simply put, Voice over Internet Protocol (VoIP) calls use internet technology to support voice calling, and Session Initiated Protocol (SIP) is the set of ‘rules’ used to make those calls and connect multimedia sessions.

The main difference between SIP and VoIP? VoIP is limited to transferring voice data over the internet, whereas a SIP trunk has the ability to transfer packets of multimedia data. This could be voice, text messages, or video.

They also operate in different mediums.

A VoIP call happens solely over the internet or a private internal network. A SIP trunk, however, can be used to transfer data packets over any network, including the ISDN (physical phone network), a VPN, or the internet.

One of the main impacts of this difference is the fact that a VoIP phone requires a computer to operate its software and connections whereas SIP equipment can operate separately.

Finally, SIP trunking is a part of the network you run your calls on.

The protocol is stored in the phone exchange that you’ll have in your building and on the network providers equipment. You can even get a direct connection to your network provider for an extra layer of security if you handle sensitive data.

VoIP calls, on the other hand, are all controlled from a central location by a separate provider that controls the traffic.

Not only is that not as secure, it means that if their system goes down, but you also won’t have any calling capability.


To best understand the difference between SIP and VoIP, let’s break these two terms down into the basic definitions.

What is VoIP?

This is a broad term used to reference any and all phone calls that are made via the internet, as opposed to via a traditional phone line. This means that VoIP relies on data connectivity instead of your standard PSTN (public switched telephone network).

Like we said above, the IP in VoIP stands for “Internet Protocol” and is an overarching term used to describe data being transferred over the internet. When this is used to describe voice data, it’s more commonly referred to as VoIP.

VoIP is a way of describing a way to bundle all these call sessions together from one user. It’s an industry term and just makes it easier to indicate how many groups of calls you might need at any one time.

Features and general qualities of VoIP can vary depending on the type of service, so these pros and cons can change. In general though, keep these in mind when considering VoIP services:

VoIP pros

Benefits of standard VoIP pros are:

  • Basic VoIP service plans include caller ID, call forwarding, and call waiting.
  • VoIP systems don’t require on-site installation and tend to be easy to transport.
  • Investment costs are typically low.
  • Most providers don’t require long-term contracts for service.

VoIP cons

With that said, VoIP can include the following downsides:

  • Lack of support of multimedia communications, as this is a voice-only service.
  • Cannot be integrated with some applications, including Pindrop and Genesys.
  • Requires bandwidth for call quality of service (QoS) and for service availability.

What is SIP trunking?

SIP or “Session Initiation Protocol” is a set of rules that are used in multimedia communications to initiate and terminate data transfer between different users.

To best compare SIP vs. VoIP, it’s good to consider how VoIP can be improved by using SIP trunking in tandem. Consider the following pros and cons for combining the two:

SIP trunking pros

Adding SIP can give your business a lot more flexibility.

For example, SIP trunking makes it easier for your company to:

  • Send multimedia messages and improve scalability by adding video and other kinds of messaging.
  • Gain more pricing flexibility by allowing for additional lines or features if necessary.
  • Improve integration with PRI lines.
  • Provide a failsafe for employee’s devices if there is ever an issue with data connectivity.
  • Better integrate with cloud-based applications like Unified-Communications-as-a-Service (UCaaS).

SIP trunking cons

Versatility and cost can make SIP trunking a great answer to your problems, but there are still some drawbacks to consider:

  • Service quality will be difficult to maintain without sufficient bandwidth.
  • If used on the public internet, SIP can have issues with security and quality.
  • Not all SIP providers will give the same quality of service or features you’re looking for, so make sure you’re making the best choice for your business.

Interested in learning the ins and outs of SIP trunking? Take a look at our ultimate guide for everything you might need to know.

SIP trunking vs VoIP: Which is best for your business?

With all of this information in mind, how do you make the best choice between VoIP and SIP trunking for your business?

Know first that the comparison between the two is not as direct as it may appear. Second, consider how important it is to have more than voice-only services.

If you want additional features, it might be useful to get SIP, which offers multimedia communication and flexibility.

Still have more questions? Talk to a Bandwidth expert to learn more.