Strategic and seamless telecommunication is the secret of any organisation's success.

A decade before, companies used to rely on PRI for regional telephone connections. But now businesses need a faster, smarter and more reliable approach to streamline communications.

Here's where SIP Trunking becomes useful, transforming modern business communications.

SIP Trunking is a requirement for companies of all sizes, not merely a technological advancement. It gives your company the ability to expand, work together, and communicate with customers anywhere in the world—whether you're a startup or an established company. It's the future of communication, not simply a choice, that will keep you one step ahead of the competition.

In this article, we will discuss why a business should transition from PRI to SIP trunking and what key differences make SIP trunking a better choice for a business.

Understanding SIP Trunking

SIP Trunking (A.K.A Session Initiation Protocol Trunking) is a telecom technology that has a lot to offer your company. SIP Trunking is an internet-based method of making and receiving phone calls.

It functions similarly to a virtual phone line and uses an internet connection to link the public switched telephone network (PSTN) and your company's Private Branch Exchange (PBX) system.

PRI (Primary Rate Interface) in telecommunications

PRI, or Primary Rate Interface, is a traditional telecommunications technology. It's an ISDN (Integrated Services Digital Network) variant made specifically for use in corporate settings.

When connecting a Private Branch Exchange (PBX) system to the public switched telephone network (PSTN), businesses hitherto mostly depended on PRI. 

It was perfect for companies that received many calls since it provided consistent, high-quality voice calls. But due to developments in telecommunications technology, many companies are now switching to more adaptable and affordable options, including SIP Trunking, which uses the internet to transmit data and voice calls.

SIP Trunk vs. PRI: a detailed comparison

Type of connection: 

  • PRI: The Public Switched Telephone Network (PSTN) is connected to the digital network via physical connections through copper cables and dedicated circuits. 
  • SIP: SIP Trunking, in contrast, uses IP networks to create virtual connections to the internet. Because it isn't dependent on actual copper wires, it is more adaptable and affordable.


  • PRI: PRI is usually only accessible from one physical place, which is onsite or within the building.
  • SIP: Through third-party SIP Trunking providers, SIP Trunking provides the option to be situated either locally or offshore in the cloud. Users may use their phone system from almost anywhere with an Internet connection thanks to this cloud-based solution.


  • PRI: PRI is less mobile-friendly due to its physical connection need, which limits its use to a certain area.
  • SIP: Mobility is provided using SIP Trunking, which enables customers to access their phone system from a variety of gadgets and places with an active Internet connection. Businesses that use mobile or remote staff would particularly benefit from this flexibility.

How many lines are concurrent? 

  • PRI: Provides a certain amount of channels per connection, usually twenty-three. 
  • SIP: SIP Trunking offers the option to have an infinite number of concurrent lines and is very scalable. Trunks may be readily added or removed online by users to suit their own needs.

Necessary hardware: 

  • PRI: It requires physical infrastructure, such as wiring, physical lines, an onsite PBX, and recommended PRI phones. A specific room is also needed for an internal phone system. 
  • SIP: SIP Trunking is an affordable solution that works with current hardware, including desktop computers, mobile devices, IP phones, and other gadgets. It is not dependent on a specific physical infrastructure. 

Oversaw by:

  • PRI: An internal IT team or technician is often in charge of managing PRI systems, which may call for specific knowledge.
  • SIP: SIP Trunking offers flexibility in terms of management and maintenance and may be handled by in-house or contracted IT specialists, as well as by a third-party SIP Trunking service provider. 


  • PRI: Due to the physical installation required for new PRI lines and the fact that they are only available in set increments of 23 channels—neither more nor less—PRI's scalability is restricted.
  • SIP Trunking: It is incredibly scalable. Within minutes, users may quickly add new SIP trunks (lines), select the precise number of trunks they require, and buy bundles of trunks.

Why PRI is becoming obsolete

Well, this is clear when the internet runs everything smoothly. Why would a business invest in physical infrastructure?

Moreover, there are a number of reasons why businesses are moving away from primary rate interface (PRI) and towards more advanced, adaptable telecommunications options.

The following are the main causes of PRI's obsolescence:

  • Inadequate scalability: Scaling PRI is not an easy task. You frequently need to install more physical circuits or lines to add more lines or capacity, which can be expensive and time-consuming. It is difficult for enterprises with varying communication demands because of this constraint.
  • High prices: When weighed against more affordable options like SIP (Session Initiation Protocol) Trunking, PRI services can be pricey. Large monthly rates, long-distance costs, and costly hardware purchases are frequently associated with PRI.
  • Non-adaptability: Because PRI connects phone lines to specific places, it may not be an option for companies who want to offer flexible work schedules, have remote employees, or have various locations. It is less flexible in the face of the contemporary workplace.
  • Absence of high-tech features

Furthermore, it lacks the features and functionalities that modern enterprises need for effective communication. Features like voicemail-to-email, video conferencing, and unified communications are among the things that modern businesses need, but PRI finds it difficult to deliver. Moreover, PRI has limited disaster recovery options. In the event of an outage, rerouting calls can be challenging, as it relies on physical infrastructure that may be disrupted.

The biggest challenge is PRI does not easily integrate with newer communication technologies, such as cloud-based systems or unified communications solutions. This makes it less suitable for businesses seeking to leverage modern communication tools.

Due to these constraints and the advancements in communication technology, PRI is progressively losing its relevance. Modern, affordable, and adaptable solutions like SIP Trunking—which offer improved functionality, scalability, increased flexibility, and interaction with the newest communication tools and services—are being used by a growing number of enterprises. If your company still uses PRI, you might want to switch to a more reliable telecom option in the future.

Here's how you can switch from PRI to SIP trucking.

Transitioning from PRI to SIP Trunking

Making the switch from PRI to SIP Trunking is a calculated manoeuvre that has to be well thought out. This is a step-by-step approach to assist your company in navigating this change:

  • Assess your current infrastructure: To start, identify the voice network that you currently have. Take a look at your communication demands, the amount of PRI lines, and how they are used. Think about things like the placement of your communication equipment and scalability.
  • Pick a SIP Trunking service provider: Find a reputable SIP Trunking supplier by doing some research. They will help with the migration procedure and supply your SIP trunks.
    Tata Communications can facilitate a seamless transition from PRI to SIP Trunking for your business. Tata Communication Global SIP Connect is an innovative and tailored global SIP Trunking solution.
  • Select the architecture and access: Choose the strategy for deploying your SIP. You have two options: you may go with a service that offers both SIP trunks and access facilities, or you can pick "Over The Top" (OTT) SIP, in which SIP trunks are provided over your current IP connection (such as an Internet circuit). Ensure the IP access/transport is appropriate for the needs and capabilities of your company.
  • Examine your network architecture: Determine whether your network architecture has to be modified to use SIP. Think about if you want to go from a centralised architecture where SIP trunks are shared for the entire company to a dispersed model with local PRI lines. Enhancements in efficiency may arise from the centralised model.
  • Session Border Controller (SBC): Install a Session Border Controller at every location that receives SIP trunks to guarantee seamless SIP Trunking. Note that certain components may have different lead times.
  • Transitioning from PRI to SIP for faxing: If your company still uses fax machines, find out if your provider will continue to support fax traffic via SIP. Make sure everything is tested and configured correctly, taking compatibility with T.38 or G.711 into account.
  • Number porting is a complex process that involves transferring phone numbers from your old PRI provider to your new SIP provider. Set time to handle port orders, keep thorough records, and ensure the transfer goes well.
  • Plan ahead: It's advisable to begin the changeover before a rise in your PRI prices or the termination of services. Even though a one-to-one PRI-to-SIP conversion is rather simple, bigger enterprises with intricate designs need to work with providers to make the change go smoothly.


In conclusion, SIP Trunking isn't just a solution; it's a transformational journey that addresses your business's pain points and propels it to new heights. With cost savings, flexibility, advanced features, and global connectivity, it's your key to staying competitive and efficient in today's dynamic world.

So, take that leap forward, unburden your communication woes, and embrace the future with SIP Trunking. Your business deserves it, and the benefits will speak for themselves, ensuring you're on the path to success, one call at a time.

Moreover, with global expert Tata Communication, you can expect a smooth transition.

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