SIP Trunking vs PRI: What’s the Difference?

SIP, VoIP, PRI, ISDN – the list of technical acronyms in the telecommunications industry never seems to end.  And when you’re trying to choose the best communications solution for your business, all of the jargon can be a real stumbling block.  To help you make the right choice for your business’s needs, we’ll compare SIP trunking vs PRI, and help you understand how each solution really works.

You’ve been tasked with choosing the best communications solution for your business, but there’s just one problem: you’re not really a technical person.  And as you scour the Internet for clues, you keep running into terms like SIP trunking, PRI, and VoIP.  As far as you’re concerned, the terminology used in the telecommunications industry is a completely foreign language.

Sound familiar?  You’re not alone.  (Seriously, we get questions about these terms all of the time.)

To make things simpler, we’ll clear up one of the most frequently asked questions, SIP trunking vs PRI…what’s the difference, and which is right for me?

What is SIP trunking?

SIP trunking is a service that connects your existing phone system to the cloud, which allows you to make and receive calls over your data network.  A SIP trunk, which is essentially a virtual phone line, replaces your connection to the phone company.  And when you make a long distance call, it will go through the Internet to the person you’re calling, rather than being routed through physical phone lines.

What is the PRI?

PRI, which stands for the Primary Rate Interface, is the standard telecommunications interface that is used by the phone company.  PRI uses physical connections (usually T1/E1 lines) instead of virtual ones, and is sometimes used to connect digital PBXs, or cloud-based phone systems, to the PSTN, or the Public Switched Telephone Network.

SIP Trunking vs PRI: Which is Better?

Although PRI was the norm for many years, SIP trunking has slowly begun to take its place.  Some of the advantages of SIP trunking include:


For one thing, SIP trunks are far more scalable than the physical connections used by PRI.  If you need to add 4 or 5 more lines and you are using SIP trunks, your provider can generally provision the additional trunks within 24 hours or less.

If you need to add 4 or 5 more lines and you’re using PRI, you’ll have to place an order or additional connections, and someone from the phone company will have to come and install them on your premises.

Cost Savings

Because SIP providers terminate calls at a much lower rate than the phone company, international calls are far less expensive, and inbound and local calls are often free.  (This varies from provider to provider, so you’ll want to ask about specific pricing plans if you’re shopping around.)

SIP trunking also eliminates the need for separate voice and data networks, which helps you save money and use your existing resources more efficiently.

Disaster Recovery

Another key advantage that comes with SIP trunking is its ability to connect with multiple offices or locations within an organization.  If there is a power outage or some kind of emergency, your provider can automatically re-route your calls to an office that has not been affected.

Since PRI connections are physical, they just don’t offer the same level of disaster preparedness that SIP trunking can.

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