pri vs sip

What is PRI and How Does It Compare to SIP?

Understanding PRI and SIP

Did you know there are more than 30 million small businesses in the United States alone? The competition is tight, and you need to stand out with the right technology to stay ahead in your industry. 

You may have heard of two standard technologies with regards to telecommunications and networks PRI and SIP. But, what is PRI, and how does it compare to SIP?

To find out which one works better for your requirements, you need to consider some essential factors to ensure you get the right one for your business.

What is PRI?

Wondering what is PRI? This acronym stands for Primary Rate Interface. It’s a digital, end-to-end connection to manage multiple voice, data, or video transmissions in a simultaneous fashion. The process achieves this through the use of a physical line or circuit.

The physical circuit is a cable with two pairs of copper wires. It can give around 23 channels for data and/or voice. All this means is that up to 23 conversations can happen at any given time, regardless of whether it’s video, chats or the like.

If you need more than 23 transmissions, you’ll need to purchase more PRI trunk circuits. These will need a physical, on-site installation process. The length of installation depends on how many circuits you need to satisfy your requirements.

PRI technology started several decades ago and is considered an older technology compared to SIP trunking. Still, plenty of businesses rely on it for daily communications.

Related: SIP Trunking 101: The Fundamentals

What is SIP?

SIP stands for Session Initiated Protocol. It is the method that enables you to send voice communications using a data network or the internet. The types of communications you can do with SIP include instant messages, voice calls, video chats, and data transfers.

Experts consider SIP as network technology, not telephone technology. This is because the entire process happens through the internet instead of telephone lines. You won’t need telephones at all. All you need are internet-ready devices that can process SIP communications.

Each SIP communication pathway is a trunk, thus the phrase “SIP trunking.” This process can help deliver almost an unlimited number of channels or calls to and from your business.

PRI vs. SIP: What is the Difference?

When questioning what is PRI, it’s worth mentioning both PRI and SIP trunking are phone systems, but they have their differences despite letting you make voice calls to another person. 

Here are some of the differences based on specific criteria:

Backup and Redundancy

Several unpredictable events can happen, leading to disruptions in your phone service. It might be due to extreme weather conditions, power outages, internet issues, or other issues. Let’s see how SIP compares to PRI here.


Each trunk has an easy means of rerouting without making a massive impact on performance. In an emergency, you can reroute the calls to predetermined destinations such as third-party answering services. The best part is you can carry on with your business until you solve the problem and calls return to your office.

It is important to remember that businesses lose 545 hours of staff productivity due to IT outages. With this in mind, estimates show companies can lose about $1.55 million each year due to this reason alone. SIP is an attractive system since it minimizes downtime.


You can use more PRI line circuits to help with redundancy, but you’ll be in a difficult situation if your PRI phone system goes down. After all, the calls on this system aren’t reroutable during outages, making it inconvenient for your business. 

Unless you have skilled IT staff with telecom experience, you will have to call to schedule a telecom service appointment to troubleshoot and fix your problem onsite. Of course, this takes time, and your business may be offline for days.


Physical hardware has associated costs, maintenance, and space requirements. Depending on the system you choose, the hardware price, maintenance costs, and footprint will differ.


You have two alternatives when choosing this option—hosted or on-premise. The advantage of the former is it has lower upfront costs and has minimal maintenance and hardware space requirements. In most cases, all you need is a physical phone or a softphone application.

With a hosted solution, your provider handles almost everything. You save on hardware costs, maintenance and space, and get peace of mind your network is taken care of without consuming your resources.

On the other hand, on-premise solutions enable you to have physical servers on-site that you control. The connections are virtual, regardless of the type. You won’t need to install additional cables, wires, and other hardware.


This type of system needs physical connections to work. They’re actual cables installed on your business premises. The number of installed circuits depends on your business demands since a single circuit can only handle 23 channels.

Due to its physical nature, PRI phone systems can become costly. If you need more lines, you’ll end up paying the installation costs once again. It’s one of the significant drawbacks when answering what is PRI.

Related: SIP: Benefits for Business Communications


If you’re a business owner, the cost is one of your primary considerations. As with most solutions, your phone system’s fees will depend on your business’s specific needs. 


With this system, you won’t need much extra equipment. You’ll save even more when looking at the setup and maintenance costs. With a hosted system, the ongoing fees only cover the monthly access to your providers’ services. In everyday situations, you’ll get charged per channel or minute used.


Due to its technology, PRI line systems are physical, regardless of the provider. You’ll need to pay for the hardware, installation and upkeep costs. The worst part is it’s charged on top of the service access fees each month.

It also becomes more expensive the more PRI circuits you install. This isn’t a great choice when you’re trying to scale up your business and control costs.

Flexibility and Upscaling

If you’re planning to expand your business, you need to ensure your phone system can keep up. Rapid upscaling and expanding to different locations need attention. Always think of the long-term effects since it’s impractical to change phone systems every few years.

Forecast your future growth to help arrive at the right decision, but understand that you may pay for more than what you need or outgrow your current needs more quickly than you expected.


Do you need more users for your SIP system? If so, a top service provider will let you request more lines easily. With this simplicity, it’s easier and quicker for you to scale up.


A PRI system circuit will only support 23 communication channels. If you need to expand and add more users, you’ll need to buy a new circuit for another 23 channels. It’s pretty slow since a technician needs to visit your office to install these expansion circuits physically.


Another deciding factor, quality, can affect the effectiveness of your business operations. It’s crucial to ensure you have the right system choice.


Transmissions from this phone system are in HD, so its quality is excellent, but only if your network bandwidth is appropriate. If you have insufficient bandwidth, your calls will have a less desirable quality.

As a general rule, your call quality improves with bandwidth. 


Transmissions from PRI trunks are not in HD. In general, the calls are stable, but they can’t provide the same quality as HD. You can compare PRI calls to the old-school analog telephone calls since they both have low-frequency range transmissions. With video conferencing a mainstay now, providing high-quality connections is critical. 

Best use cases

Most providers will recommend a SIP system over PRI, but it truly depends on your business. Your goals also play a part when looking for the phone system that works best for you. 


This solution works best if you’re trying to save money on phone services. If you’re a business in need of many long-distance or international calls, for example, this system is for you. It’s also a great system if you want to leverage more modern communications, like video, and require mobile support.


It will be best if you have little or no access to a reliable bandwidth network. If you don’t have the capacity to support IP phones and equipment, a PRI system can help fill in the gap, especially if you only need more basic communications capabilities.

Get the Best For Your Business Today!

Hopefully, this guide helped you answer what is PRI and its differences from SIP. can help you pick the right trunking system for your business. Don’t spend more on services and features you won’t benefit from and be sure to partner with the best. Do you need SIP trunking deployments? Contact us today. 

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