SIP vs PRI: Finding the best communication solution

Maybe you’re looking to upgrade your legacy system. Maybe you need more flexibility to support a remote workforce. If you’re deciding between SIP and PRI — or a hybrid of the two — there are a number of factors to consider for your current and future requirements.

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The pandemic has brought many issues to light — including the importance of communication and collaboration, especially in a virtual world. It’s been a good time to reassess your current solution and look for ways to optimize your voice and data network.

Maybe you’re looking to upgrade your legacy system. Maybe you want to roll out a more sophisticated unified communication and collaboration solution. Maybe you need more flexibility to support a remote workforce.

Both PRI (Primary Rate Interface) and SIP (Session Initiating Protocol) connect your business to a telephone network and require a PBX (Private Branch Exchange). So what’s the difference?

PRI pros and cons

PRI Trunking requires a physical connection through a PRI circuit (via a cable with two pairs of copper wires, called circuits) that provides 23 channels for voice or data (which means 23 concurrent conversations).

While it’s an older technology, it does provide fast transmission speeds and can still be used for video chats and file sharing — with no need to rely on your Wi-Fi connection. Because it’s a dedicated line, it’s considered secure, but it only offers redundancy through secondary circuits.

Clearly, PRI isn’t as scalable as other options — it’s limited by the number of wired phone lines — but the main advantage is its high-quality voice, thanks to having a dedicated line (versus VoIP over poor bandwidth). If you need scalability, you’ll need to purchase additional PRI lines (in units of 23). PRIs require installation on your site, with a monthly fee for service as well as installation and maintenance fees.

SIP pros and cons


SIP Trunking, on the other hand, uses your existing Ethernet or fiber connection for voice communications — including phone calls, instant messages and video chats — connecting your PBX to a data network rather than a telephone line. You’ll need to consider capacity, peak traffic and network load — ensuring you have the bandwidth to support your needs.

Via VoIP (Voice over Internet Protocol), it provides a virtual connection with an unlimited number of channels. That means scalability is easy; you can add voice capacity and deploy to new locations as needed, and you only pay for the capacity you need. It’s limited only by available bandwidth.

SIP also offers two options: hosted or on-premise. Hosted solutions require little to no hardware deployment and minimal upfront investment (with a monthly fee for service), while on-premise solutions require physical servers installed on-site.

Leveraging SIP for UC&C

Another advantage to SIP Trunking is the ability to optimize your voice and data network to work with the latest in unified communication and collaboration technology. Allstream’s SIP Trunking solution, for example, connects directly to your phone system or legacy PBX to enable advanced UC&C solutions on your network.

SIP Trunking also reduces the complexity of your network, while making it more flexible, and comes with built-in resiliency — allowing you to maintain network service quality and performance during disruptions with built-in failover and re-routing options. Allstream also offers cross-border SIP solutions supporting both U.S. and Canadian locations.

Read more:

Do you have to choose between SIP and UCaaS?
How DX, elastic services will evolve SIP Trunking
Q&A: What’s next for Allstream SIP Trunking

PRI, SIP or hybrid?

If you’re deciding between SIP and PRI (or a hybrid of the two), there are a number of factors to consider: How many users do you have? How many concurrent phone calls do you need to support? What are your future needs?

What you choose will ultimately depend on your specific business needs and future goals. If your top priorities are quality and call load, PRI might be the right fit. If you’re anticipating growth, SIP might be a better option.

But it’s also possible to use a combination of both with hybrid trunking (say, using PRI for local calling and SIP for international communications). So, when it comes to enterprise communications, you can have the best of both worlds.

Find out more about Allstream SIP Trunking and check out our limited-time SIP PRI offer.

Images: PeopleImages/iStock; ipopba/iStock

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