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Which is the best trunk option to deliver voice and data into a business office - SIP or PRI? It’s a question that’s likely to get a mixed bag of answers from communication pros since both are worthy adversaries. PRI, or Primary Rate Interface, is the tried and true older tech to deliver a dedicated line for business communications. SIP, on the other hand, is the newcomer. Both have pros and cons, meaning the answer to the original question is highly dependent upon the business’s unique needs. The following info can help businesses of all shapes and sizes determine what each option can accomplish and how those facets can integrate to best accomplish with their business’s communication goals.

What is PRI?

PRI lines are a form of ISDN (Integrated Services Digital Network) lines, and they’ve been the standard telephony tech since the 1980s. These enable traditional phones voice, data, and video capacity across multiple lines. It’s end to end a single digital circuit, but that single circuit carries more than just one channel. In the U.S., T1 is used, which carries 23/24 channels within two pairs of copper lines. Telco is required for service, upgrades, troubleshooting, etc.. since PRI lines involve physical hardware to operate.

What is SIP?

Whereas PRI is a telephone technology, SIP is internet technology. It’s VoIP, or voice over Internet Protocol, that uses the internet, not a circuit, to provide voice, video, and streaming. By being virtual, these trunks don’t require additional hardware and can be used for voice without an existing PBX if the SIP provider offers hosted services. It, too, offers multiple voice lines.

PRI and SIP Pros and Cons

Some communications experts maintain that PRI trunking is superior in call quality. This has merit since, unlike SIP, PRI doesn’t rely upon a network and therefore doesn’t have the potential network jitters, losses, nor interference. Businesses needing to ensure that high-profile, critical calls maintain a certain degree of quality and reliability often go with PRI, not SIP.

On the other hand, PRI is considered the more secure of the two trunking options. And, again, this has merit because PRI is traveling a private telephone network, not the SIP internet-based lines. Businesses that opt for SIP counterbalance this risk with hardened firewalls to protect their corporate network.

Flexibility is by far considered SIP’s greatest pro and PRI’s greatest con. Most businesses don’t remain stationary in needs; in other words, most business’s ultimate goal is growth. As a business grows, their telephony needs expand. PRI businesses will have to contact the provider to upgrade, which involves a PRI tech issuing another PRI circuit at the business’s site. SIP is much more flexible at meeting growth demands since it simply requires adding more SIP trunks through the SIP provider by means of a simple online request or by upgrading a hosted service subscription to a plan with more lines or users. No on-site tech required with SIP.

SIP is also viewed as more cost-efficient than PRI. Little, if any, hardware is required of SIP trunking.

Research will be required for usage rate comparisons between the various providers of both SIP and PRI. Both have competitive pricing points that vary by location. The main caveat to consider is how service is billed. Some providers offer a flat rate for usage. Other providers can have rates based on usage that accumulate next to a standard telephone bill.

Internet down time is another consideration with SIP. Without a separate failover internet connection in place, the business’s SIP telephone system will be down whenever the internet is down.

Evaluate Business Needs For SIP Versus PRI Trunking

When considering trunking options and which is right for a particular business, it’s important to look specifically at the communication needs there of and how either option would impact the business’s communication for better or worse.

Consider the users. How many people are typically simultaneously calling out and receiving calls during peak business hours? Will SIP be able to handle this call load with the bandwidth of the internet connection available through the provider options? If a large enough bandwidth isn’t available, then PRI may be a better fit.

How is the business’s IT demands met? In-house? Contracted per need? Hosted SIP solutions may be the best fit for businesses with little IT available in-house for the servicing and upgrades PRI trunks will require.

How important is call quality to the business? Does the business have a frequent number of critical, high-value, make or break phone calls that simply cannot be jeopardized by poor connectivity? If this isn’t a concern, then SIP may be a suitable choice. Otherwise, PRI would be invaluable.

What about scalability needs? Does the business need a quick method to scale the number of users and/or lines within the business? If so, SIP wins over PRI.

It might be time to either upgrade the business’s PBX or go with a hosted SIP communication solution if its existing PBX system isn’t comparable with VoIP gateways.

SIP and PRI Hybrid Trunking

As a final thought, who is to say a business has to pick one or the other trunking option. There are cases where a business may want to explore a hybrid mix of both PRI and SIP trunking.

One such hybrid example would be a business that uses SIP from a hosted VoIP service for their international calling needs while they still use PRI for local calling needs. It’s cost efficient and offers both security and flexibility as per needed.

PRI is increasingly being replaced by the newer SIP trunks. That said, SIP trunking can be used with PBX systems via a VoIP gateway.

Find out how much you can save today on SIP

Compare top SIP providers in the table below.

Image VoipPreview
Solutions Price Rating
Carefree Business SIP Trunks
  • Voice & SMS on the same number
  • Instant Number Provisioning, Nationwide coverage
  • Geo Redundant Servers, Automatic Failover
+ $0.0081/min. For US and Canada only. International rates apply

$ 9.97 /mo. *

*Rates shown do not include E-911 charges, taxes, and surcharges. Most providers offering unlimited calling have restrictions and some rates shown are promotional rates based on term contracts or promotional periods. Be sure to read individual providers terms and conditions before you buy. Rates and features displayed for each provider have been sourced from provider's site and other online sources. While we strive to display current information, be sure to check directly with each provider as their plans, pricing, and features are subject to change.

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