Is it time to move from PRI to SIP?

Posted on January 8, 2018 by Andrea Mocherman

There is no denying that the world is moving to IP, and SIP has become the de facto communications solution of choice for business connections. According to Technavio’s analysts, the Session Initiation Protocol (SIP) Trunking market is expected to grow at a compound annual growth rate of 18.23% by 2021. Topping the list of reasons that businesses are migrating away from PRI over to SIP trunking are improved reliability, flexibility, and cost-effectiveness.

Before we jump into those, let’s first get a better understanding of what PRI and SIP Trunking are.

What is PRI?

A Primary Rate Interface (PRI) is the legacy method of providing telephone service to larger businesses with a digital PBX. PRI operates within the Integrated Services Digital Network (ISDN) specification for transmitting voice and data between a network and a user. It’s based on the T-carrier (T21) line consisting of 24 channels, 24 for voice and one for signaling. For the business user, this equates to 24 lines for phone service and a limit of 24 concurrent channels, hooked up directly to the telephone company’s central office.

What is Session Initiation Protocol?

Session initiation protocol (SIP) is an application layer protocol similarly used to transmit voice and data between a network and a user. SIP supports the standard call processing functions found in the public switched telephone network (PSTN) for IP-based networks.

SIP Trunking establishes virtual voice circuits configured and delivered over an Internet connection. Used in conjunction with an IP PBX or traditional PBX with an IP gateway, businesses gain a much more robust replacement for traditional PRI or analog circuits at a fraction of the cost. Outside of dramatic costs savings, SIP also enables businesses to digitize their communications, unlocking a whole suite of features that were previously inaccessible on a PRI system.

There are plenty of factors to take into consideration when choosing the right SIP Trunking provider for your migration to satisfy your business needs. Below you will find the top three drivers for making a move from PRI to SIP Trunking.

Improved quality and reliability

Voice quality is one of the top priorities when looking for a SIP Trunking provider. Flowroute takes a different approach to media delivery, which utilizes software to establish direct communication between the endpoints and reduce the latency and jitter of a call. In the event of degradation in call quality, we can research and diagnose the problem across the entire call path and if necessary assign a new inbound route through our patented HyperNetwork™ to complete the call successfully.

Increased flexibility

SIP is designed to be a flexible, more user-friendly alternative to PRI. Some providers understandably model their systems after traditional telecom providers, limiting enterprises both in terms of capacity and functionality. By definition, SIP should provide the freedom to configure your system to meet your specific needs and simplify the overall management of your telephony environment. Make sure you ensure your carrier isn’t limiting your capabilities.  


Cost is now the big driver behind today’s SIP sales. It displaces “anytime, anywhere communications” as the key catalyst. SIP trunking easily costs 50% less than traditional networks according to a recent Eastern Management Group report. It is important to note that a cost-effective solution is important but not at the expense of voice quality. So finding a software-centric carrier like Flowroute that offers the highest voice quality in combination with affordable pricing and wholesale rates is key to a successful migration.

In addition to these key drivers, businesses need to ensure the SIP Trunking provider they work with has the following key features before they make a move.

A self-service portal that gives you complete control over your telephony system.

  • The ability to instantly provision a SIP trunk and be live as fast as you can configure your IP-enabled PBX.
  • A reliable failover plan in the event of a DDoS attack or network outage to limit downtime.
  • The ability to easily purchase and activate DIDs and toll-free numbers.
  • Automated porting capabilities to reduce the headaches of switching providers.
  • Proactive fraud monitoring to protect customers from telecom hackers.
  • Real-time reporting for immediate insight and analytics.

Stop wasting money and resources on PRI. Flowroute SIP Trunking gives you a better way, with more flexibility, higher quality, and cost savings through one provider. With thousands of customers deployed, Flowroute is here to help you optimize your voice services today!