SIP Trunk vs. PRI: The pros and cons

While SIP and PRI both offer similar outcomes for your business, they each have different benefits to offer. Here's everything you need to know...

Mike Mead


Communication is at the heart of any successful business.

If you think it’s time to take your company to the next level, one of the best things you can do is invest in new communication technology. After all, when you upgrade your comms stack, you help your team members stay connected, while also delivering a better level of service to your customers.

Two of the most commonly considered protocols for communication include VoIP delivered over SIP or PRI phone systems. While both options can offer similar outcomes for your business, they each have different benefits to offer.

Let’s take a look at PRI vs. SIP.

What is PRI? The pros and cons of PRI

PRI, or Primary Rate Interface, has been used for communication purposes for more than 40 years. This telecommunications technology relies heavily on your physical infrastructure. PRI has been the industry standard for companies for decades, leading the way before cloud and VoIP came into existence.

PRI uses hardware and integrated services digital network (ISDN) to manage and deliver lines of data and voice through a single physical circuit. PRI circuits offer support for up to 23 voice channels and 23 concurrent calls.

Benefits of PRI include:

  • No reliance on data bandwidth for voice calls
  • High-quality communication thanks to the dedicated line structure
  • Redundancy offered via secondary PRI circuits

On the other hand, the cons of PRI are:

  • It’s expensive to implement and upgrade, and often requires a monthly phone service
  • You may need to commit to long-term contracts with telecom companies
  • You’ll need a dedicated capacity that’s only available in 23-line units
  • PRI is slow to scale as changes to infrastructure can often take weeks

Ideally, PRI is best for companies who already have a legacy infrastructure in place and limited access to fibre-optics for their internet. You can also consider PRI for a hybrid PRI and SIP-trunking strategy if necessary.

What is SIP? Pros and cons of SIP trunking

Session Initiated Protocol, or SIP, is a solution that works alongside existing VoIP connections. These technical standards support VoIP calls and ensure that you can transmit data over an internet connection. At its core, SIP transforms your cloud network into a robust telephone system. All calls take place over your IP network, which means that there’s no need for traditional phone lines.

The biggest difference between PRI and SIP is that SIP is a telephony networking solution, while PRI is a telephony technology by itself. The benefits of SIP trunking include:

  • It’s sold on a per-channel basis, according to demand, so you only pay for what you need
  • It’s much more affordable than PRI for most companies
  • Failover solutions to mobile phones are available for continued connectivity
  • Easy-to-use administrative portals available for simple management
  • Offered via the cloud as part of a complete UC strategy
  • Can be integrated with a range of multi-media communication options for better collaboration
  • Great for multiple sites and remote workers
  • Includes opportunity to integrate with PRI lines for hybrid performance

Of course, SIP trunks have their downsides too. For instance, SIP:

  • Requires consistent internet bandwidth to support ongoing quality of service
  • Can vary in performance depending on the VoIP vendor
  • Needs sufficient network security to protect against cyber crime

SIP trunks are excellent for companies that want to save money on their business telephone services – particularly when there’s a lot of international and long-distance calling to deal with. SIP also reduces the burden of phone system management for your IT teams too, particularly if you’re planning on moving into hosted multi-channel UC strategies going forward.

What’s right for your business?

Before you invest in a PRI to SIP conversion, you’ll need to decide which option is truly best for your business. Both choices have their advantages and disadvantages. SIP is often a great selection for you if you have multiple locations to think about. You can route calls between physical locations easily, no matter how far apart they may be. Additionally, SIP is great if you’re growing rapidly with a plan for digital transformation.

However, if you don’t have a reliable network connection, then PRI may be the best choice, as SIP is reliant on your connectivity. Want to talk more about telecoms? Contact Nice Network today; we’ll help you find the right solution for you.