SIP’s emergence spells the end for PRI.  PRI represents the traditional Public Switched Telephone Network (PSTN), while SIP represents Voice over IP. To put it in layperson’s terms, SIP is the future, PRI is the past.

Major providers like CenturyLink, AT&T, and Verizon are providing SIP services now.  Business owners should wade through the two technologies to understand where telecom is headed and the best option for their current and future usage.

What is PRI?

PRI is a digital circuit providing 23 channels or voice paths and one channel for signaling.  Signaling provides Caller ID information and other data that helps the circuit perform.

PRI is a direct connection to the PSTN, so the call quality is excellent.  It is a good substitute for POTS or business phone lines when a business requires more than ten phone lines.

A business line costs an average of $40 a month.  A PRI can be had for around $500 a month, so as soon as you exceed 10 phone lines, you’re probably better off with a PRI.

Advantage of PRI

As PRI is a relatively older piece of technology, its advantages are fewer than its disadvantages. The most important advantage is that it is cost-efficient as compared to POTS. This is because of the below reason:

PRI allows for the use of DID’s at a lower cost than POTS

DID’s are phone numbers.  A PRI with DID enables a business to have more phone numbers than phone lines, offering greater number flexibility.

Typically, a PRI is “oversubscribed,” which means there are more users than call channels.  That’s possible because, in most businesses, not everyone is on the phone at the same time.

If a business had 40 employees and wanted phone numbers for every employee with POTS lines, they would need 40 phone lines.  At $40 a phone line, the cost would be $1600 a month, or more than three times the cost of a PRI as PRI costs around $500 a month.

Disadvantages of PRI

Disadvantages of PRI

There are several noticeable disadvantages of PRI, as explained below. These should form part of your decision-making process as a business owner:

1. T1 card requirement:

To utilize a PRI, a T1 card is a required component in a business’s phone system or PBX (Private Branch Exchange).  That’s not an issue in newer systems.  In an older system, a business should expect to pay between $500 and $1200 to add a T1 card.  If the business is using POTS lines, it should be easy to calculate the ROI for the purchase of a T1 card.

2. Voice communication integration issues:

With PRI, your voice communication is entirely separate from your internet or data traffic.  A new loop from one of the incumbent phone companies is required for each voice and data circuit, and a separate run of cable is necessary for a business’s voice and data networks.  A PRI can be integrated with an MPLS network, but that takes place on the customer’s premise, and their location dictates what area code and prefixes can be used.

3. Don’t make efficient use of a company’s resources

PRI’s don’t make efficient use of a company’s resources.  The unused channel sits dormant.  Each PRI offers 23 channels, so if a business required 50 call paths, they would need to order three PRI’s, for a total of 69 channels. This leads to unused 19 unused channels. Another option is to try to get by with only two PRI’s and 46 channels.

The above disadvantages lead to the newer SIP technology that can overcome some of the abovementioned flaws of the PRI technology.

What is SIP?

SIP is Voice over IP, so your voice calls are transmitted across the internet, along with emails, data files, etc.  The call quality can range from not great to very good, depending on the network it is being transmitted on.

What is SIP

Most carriers offer QoS (Quality of Service) and CoS (Class of Service) on their MPLS networks.  MPLS or Multi-Protocol Label Switching is a type of wide-area network that facilitates VoIP.  QoS and CoS are standards or settings utilized to assure call quality.

The most critical difference between PRI and SIP is that SIP trunks or the call paths can be ordered in any increment, unlike the 23 channel minimum order under PRI.

Advantages of SIP

Originally, SIP was sold by smaller companies that didn’t own a network or provide the customer’s internet connection.  This led to poor call quality and shoddy performance, causing some business people to be leery of VoIP, but now carriers offer unified solutions that assure call quality. So SIP is one of the most upcoming solutions for VoIP, internet, and telecom requirements. Below advantages explain how:

1. Efficient use of resources

SIP provides more efficient use of resources because voice communication rides over a business’s data network.  Below are a few contributors to the efficient use of resources:

  • Easier network management: There is only one network to manage and only one set of cables required. This implies that you only have to manage one setup
  • Alternative usage: SIP uses the already existing data network for VoIP, and the same bandwidth is freed up for data usage if the SIP trunks aren’t in use. So, nothing goes unused, or there is no idle capacity
  • No minimum increment requirement: Businesses are not required to order call paths in increments of 23. They can order only as much more is needed, so you pay for only what you use
  • Improved resource sharing: SIP trunks can be aggregated at the company’s host location, and trunks can be shared company wide, so economies of scale can be realized.

2. Flexibility


SIP allows for even more phone number flexibility and functionality.  You can incorporate traditional DID’s, and out-of-area DID’s, so you can make any number ring at any location nationwide.

It also allows for failover.  Should a company location or call center get knocked out by a natural disaster, the company’s phone numbers can be routed to a separate location.

3. Time to implement

Unlike PRI, additional SIP trunks can be implemented in days, not weeks. This is one of the most practical benefits of SIP over PRI because no fast-paced working environment can afford losing time. If accuracy can be achieved faster, every business prefers a faster technological implementation.

4. Simple Acquisition

Competitive Local Exchange Carriers (CLEC’s), like TW Telecom and Integra, offer SIP much the same way as more traditional integrated T1s.

They sell SIP trunks in packages that include internet access, call paths, and long-distance minutes. Further, the services are delivered in a manner that they will function with analog or digital phone equipment.

This makes acquiring the new technology simpler, leading to greater acceptability.

Disadvantage of SIP

Although the SIP technology is a massive improvement over the PRI, it is not free from flaws. Below are some disadvantages of this technology:

1. Integration Implies Complete Failure:

As Voice and data networks are shared, your business can lose all forms of communications if there is an internet failure. Although the chances of that happening are very remote, it is still a possibility. Therefore, it is advisable to have at least one backup option to prevent complete cut-off.

Lack Of Security

Where there is the internet, there is a chance of hackers gaining access to all your calls. If you deal with sensitive information, that shouldn’t be transmitted over SIP. Day-to-day information might not cause much harm; however, confidential information must be secured from unauthorized access.

Last Few Talk on PRI vs SIP

To sum up, PRI technology provides voice communication over the phone network, while SIP technology provides voice communication over the internet.

SIP is a more versatile, scalable, and resource-efficient technology that is becoming the future of telecommunication. PRI is a legacy system and will be phased out over time.

SIP is the clear winner between the two technologies, based on the above discussion, the only factor that still makes PRI relevant is the need for confidentiality. This is where SIP still needs to improve. So, based on the nature of information you access as part of your work, you can decide which technology is more appropriate for you.

If you would like to receive more information regarding SIP or consultation on moving your voice communication from PRI to SIP, call CarrierBid today or complete the form on the right side of this page.  We will help you figure out which technology is best for you.

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