PRI vs. SIP Trunking: Proven protocols for ever-important voice service

Despite what The Buggles lamented in their 1979 hit song, video hasn’t “killed the radio star.” It also hasn’t caused the demise of the phone call. Because even with the recent surge in videoconferencing, we still rely on voice to communicate with customers, team members and vendors. And right now, voice is having a moment. With the popularity of podcasts and the surprising allure of audio rooms on social media apps, voice communication is as vital as ever. Which begs the question: What’s the best voice technology for your business?

Let’s look at two common options: PRI and SIP Trunking. Both are proven protocols for delivering high-quality voice calls. And that’s where the similarities end. 

What is PRI?
Primary Rate Interface (PRI) has been around forever in technology years—more than four decades. It uses the Integrated Services Digital Network (ISDN) to transmit calls and data through one line of a business’s Private Branch Exchange (PBX). Each PRI circuit consists of 23 voice channels, which means it can support 23 lines on a single connection. 

What is SIP Trunking?
Session Initiation Protocol (SIP) Trunking transmits voice and unified communications like video calls, collaboration apps and file sharing over the internet, making Voice over Internet Protocol (VoIP) possible. The technology uses a packet switch network to divide voice calls into digital packets, creating a virtual phone line. 

PRI’s update (It’s complicated)
You might think PRI is immune to hacking because it transmits signals over copper wires versus the internet, but unfortunately, bad actors can interfere with and tap into phone lines, too. That said, some might take comfort knowing PRI doesn’t rely on the internet. If there’s an internet service outage, you can still make calls. So if you have spotty bandwidth, PRI might be a good choice. An even better choice? Upgrade to Dedicated Internet Access for 99.999% reliable connectivity. 

PRI downsides
PRI is a bit of a dinosaur. A PRI circuit is a physical connection, so if your business requires many communication channels, this could lead to high deployment, installation and maintenance costs. Everything must be done on-site with experienced technicians tending to circuits and expensive hardware. Oh, and if you want to add a line? You have to add 23 lines, whether you need them or not.  

Something else to consider: PRI is an older technology and as more companies migrate to SIP, it could become a challenge to maintain in terms of available equipment and expertise. Besides, your IT team has enough on its plate. Why not take your phone system off it?

SIP upsides
SIP is cost-effective and easy to deploy, maintain and upgrade—without taxing your IT team. You can add lines remotely, one at a time, as needed. Depending on your SIP provider, you may even be able to say goodbye to long-distance calling fees or purchase in convenient, bundled time increments.

And regardless of where you are in your digital transformation, if you haven’t migrated to the cloud yet, chances are you will soon. In our work-from-anywhere world, Unified Communications and virtual collaboration tools are necessary for most businesses, and PRI simply can’t support them. 

SIP downside
If you can call this a downside: With SIP, the quality of your internet connection determines the quality of your calls. If your internet is slow and unreliable, it could be a problem. But if you have an enterprise-grade, private connection with an SLA, it’s not an issue. 

Which side of history do you want to be on?
The writing is on the wall: PRI is on the way out and SIP is the way forward. SIP is cost-effective, easy on IT teams, super scalable and the way of the future. Unless you truly aren’t growing, are entirely brick-and-mortar and are unlikely to benefit from digital technologies. In that case, sticking with PRI is the better choice. 

What to look for in an SIP Trunk provider
When evaluating SIP providers, look for one who guarantees five nines: 99.999% availability. Because with SIP, your internet is your phone line and it needs to be reliable. Also, find out if your provider can prioritize voice traffic to ensure call quality without compromising your bandwidth. Most important, team up with a partner who will assign dedicated experts and a single point of contact to your account.