learn the difference between SIP trunking vs PRI

SIP Trunking vs PRI 101

Nicholas PriceLast updated on September 27, 2023
9 min

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SIP trunking vs PRI 101 is a topic that’s technical and confusing for most people. Even so, they’re very important terms in the phone industry. Every time you make a phone call, you take for granted that the call will go through quickly and reach the other line, whether someone picks it up or not.

Behind the scenes, either SIP trunking or PRI is at work connecting the signals to complete the call. The differences between them have a big effect on the calling capabilities for your business. By understanding more about business phone systems and taking stock of the features that enhance your operations, you’re positioned to find the phone system that’s right for your business.

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Understanding SIP Trunking vs PRI

Understanding SIP trunking vs PRI might seem like sorting through a technical alphabet soup of phone system terms. SIP trunking and PRI are similar in that you can use either system to make a voice call from one person to the other. The important difference between SIP trunking and PRI is that each of them uses a different technology setup.

The difference in the setup for SIP trunking and PRI are a matter of function. For businesses, the differences create some important considerations in these areas:

  • Connection

  • Transmission

  • Scalability

  • Hardware

With SIP trunking, you have a virtual connection through the internet. Your calls travel from one point to another through your internet connection via data packets. SIP connections are only limited by the amount of bandwidth that you have.

A PRI system has a physical connection through a PRI circuit connection, and calls are transmitted through physical circuits. When it comes to scaling your call capability, PRI is limited by the number of standard phone lines you have.

Advantages of SIP Trunking

SIP trunking has a number of advantages over PRI for your business. The advantages are valuable enough that most companies are already using this type of technology.

Here’s a look at what some of those advantages are:

  • You don’t need extra equipment

  • Low cost for set up

  • Low cost for maintenance

  • Save even more with hosted SIP

  • Only pay a monthly service fee

  • Can reroute your calls with little interruption if the system goes down

  • Can add users quickly and easily-scalability

  • Clear calls (with proper bandwidth)

  • Need little or no in-house IT help

What Is SIP Trunking?

The SIP in SIP trunking stands for session initiated protocol. In simple terms, SIP means a process of sending voice communication over the internet. Communications can also include instant messages, video chats, and data transfers.

In a practical sense, with SIP trunking, you place a call and it gets transmitted through the internet to your phone service provider. From there, your carrier takes the call and sends it to the person you called over the internet as well. With SIP, you don’t need a telephone at all. You just need a device that’s internet ready.

SIP is sold in channels—usually by the batch. Providers group them by the amount of bandwidth they need to transfer a call. Phone service providers set up channels according to the number of calls your business normally has at any given time. Each communication channel is called a SIP trunk, which is where the term SIP trunking comes in. You can add or remove channels easily at any time, and that means you can scale your phone system or your call center up or down easily. SIP trunking gives you almost limitless channels for communicating.

From a technical perspective, since SIP transmits communication over a data network, it’s considered network technology. This is in contrast to the technology that PRI uses which is telephone technology.

There are two types of SIP trunking—on-premise solutions and hosted PBX solutions. Here’s a snapshot of each of them.

Hosted PBX Solutions

  • Doesn’t require having an on-site server

  • Only a small upfront cost

  • Requires only no hardware or maintenance

On-Premise Solutions

  • Requires a physical server on-site

  • All connections are virtual

  • No additional installation for cables, wires, other equip

SIP Trunk Implementation

A few tips will make SIP trunk implementation go smoothly.

  • One entity should be responsible for overseeing setup and operation.

  • Have a process in place for system management and real-time monitoring.

  • Know who is responsible for solving a problem at any given time during integration and operation.

  • Put specific responsibilities in the requirements and assign them to specific vendors-get the name, title, and contact information of responsible employees.

SIP Trunk Design

Keep these things in mind when it comes to SIP design.

  • Fully understand the customer’s needs.

  • Perform a cost/benefit and risk analysis, including new equipment.

  • Ensure sufficient bandwidth for shared services.

  • Calculate the cost of end-to-end management.

Which Type of Business is PRI Suited For?

There are three situations where a PRI might be better suited for a business than SIP trunking:

    1. Businesses that already have a PRI infrastructure in place.

    1. Businesses that don’t have access to a reliable internet service.

    1. Businesses that don’t have enough bandwidth to support internet phone systems.

What Is PRI?

PRI stands for primary rate interface. It’s a 40-year-old technology that makes it possible to transmit voice communication over standard phone lines via physical copper wires (also called a circuit).

While the technology is substantially older than SIP trunking, it’s not always better for all businesses.

PRI circuits include 23 channels for data or voice and they can support 23 calls at the same time. If your business needs more than 23 voice channels, you’ll need additional channels. Unlike SIP trunking where voice travels in data packets, PRI data travels using electrical pulses that route across traditional phone companies, so you’ll need to have an account with a traditional phone company.

If you’re using a PRI system, you’ll be responsible for the costs of installing cables, repairing cables, adding lines, and upgrading equipment.

How PRI Works

From your perspective as a caller with a PRI system, you pick up the phone and dial a number. The call goes through the PRI cable and the phone company picks up the call and sends it to the person that you’re trying to reach.

If you are trying to decide whether SIP trunking or PRI is best for your business, the following advantages and disadvantages will help you decide.

Advantages of PRI

  • PRI lines are capable of transmitting data, fax, voice, and videoconferencing at the same time.

  • One PRI phone line costs far less than dozens of analog phone lines.

  • Digital quality is far better than analog phone technology.

  • Digital lines are more reliable than analog phones.

  • PRI lines connect faster than analog lines.

Cons of PRI

  • You have to install cables on the premises.

  • You have to maintain the cables and you’ll have monthly fees also.

  • You’re limited to 23 channels for each cable and if you need more channels, you incur the cost of installing more cables.

  • If you lose a connection due to the weather, a power outage, or the internet is down, you can’t reroute calls to another line.

What Features Should You Look for in a SIP Trunking Provider?

From a technical standpoint, there are a few important features that you should look for in a SIP trunking provider:

  • Computer Telephony Integration (CTI) – customize workflows and improve productivity with one click.

  • Webhooks & API – Use them to connect your everyday digital tools or build a new custom workflow.

  • Contact Synchronization – Build your network of shared contacts.

  • One-Click Setup – Activate integrations with one click and manage all settings in one place.

  • Insight Cards – Pull related data from other apps into view.

Besides making it easy to switch to SIP trunking, Aircall delivers a host of phone system features for immediate use in your office and with your call center. These are some of the features you can get with call center software:

  • Toll-free and international call capability

  • Interactive voice response (IVR)

  • Virtual call center

  • Call queueing and queued callback

  • Voicemail

  • Call conferencing

  • Shared contacts and shared call inbox

  • Call commenting and assignment

  • Warm transfer

  • Call recording

  • Routing that is call-based and skill-based

  • Click-to-dial

  • Call tagging

And much more.

How Can You Get Started with SIP Trunking?

The best way to get started with SIP trunking is by using a SIP trunking provider that takes the hassle out of setting it up. Aircall simplifies the process of making the switch to SIP trunking. You won’t have to juggle multiple contracts when you choose Aircall as your SIP trunking provider. The Bring Your Own Carrier model (BYOC) that Aircall uses ensures that you get the best provider and quality coverage no matter where you call in the entire world.

With Aircall at the reins, you can get rid of your desk phones and use a cloud-based phone system. Instead of using expensive PRI cables, Aircall uses modern softphone WebRTC technology and it lets you transmit calls through web browsers, web apps, and mobile apps.

Aircall connects your calls to the cloud and the cloud connects to a computer, tablet, or smartphone. Aircall then initiates SIP trunking through the provider that’s best suited to complete the call.

How to Choose Between SIP Trunking vs PRI

That’s a lot of technical information to sort through. To make it easier to choose between SIP trunking and PRI, here’s a short-list of how to compare them:

Flexibility and Upscaling

Your business may grow now or in the future. That might mean adding a call center, adding agents to your call center, or adding some new facilities. If you encounter a crisis, you might need to downsize your call team. Those are the times when flexibility and the ability to upscale become important.

Remember that with PRI you only get 23 communication channels. It will be expensive to add even one more user. With SIP, all you have to do is contact your phone service provider and it’s as good as done.

Quality of Service

Calls are generally stable with PRI transmissions even though they’re not in HD. The quality may be less than with network communications because it uses a low range frequency. SIP transmissions are in HD, so the quality is usually excellent as long as you have sufficient bandwidth.

Amount of Bandwidth

This goes back to the issue of 23 channels for PRI. Anticipate the maximum number of calls that you expect to receive at any time. If you have a call center or a sales team, SIP trunking will be the hands-down winner.

System Compatibility

If your current system is compatible with VoIP gateways, it will work with SIP trunking and you’ll be on your way to a modern phone system. If it’s too old, you’ll either need to stick with PRI or update your system completely.

Access to IT Support

With a PRI system, you’ll need help from IT experts. You’ll need to call on them to troubleshoot, maintain, and upgrade your system. With a hosted SIP trunking system, there’s nothing on your part to do. The host takes care of it all.

To simplify things a bit more, here are reasons why SIP works better when it comes down to SIP trunking vs PRI:

  • Want to save money on phone service

  • Need to make a lot of long-distance or international calls

  • Need to make mobile calls

  • Have or plan to have remote teams or distributed teams

  • Would like to reduce your on-site IT staff

  • Would like to use multi-channel communications

  • Want to modernize your phone system by updating to cloud communications

  • Need the ability to scale up or back quickly

At the end of the day, modern times call for doing your homework when it comes to changing to a new phone system. When you’re ready to move from PRI to SIP trunking, you’ll now have the technical information to make it happen. If modernizing your phone system isn’t right for your business currently, it’s good to have in the future.

Aircall provides the right setup and features for you to run an effective call center. When you change to Aircall, you’ll find many new opportunities to improve customer service and streamline your operations.

Published on September 23, 2020.

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