Home  >  Telecom Equipment  >  Internet Access  >  Which One To Choose For Your Business, SIP Trunk Or ISDN PRI?
Which One To Choose For Your Business, SIP Trunk Or ISDN PRI?

When we talk of any technology, we realize that just at the moment we think we have got the access to the best technology; something new will come up as a surprise and prove to be better than the technology we are focusing on.  One of the latest technology to be included in this parcel is VoIP based SIP Trunks, which is greatly increasing its horizon in the field of communication technology all over the world. 


For quite a long span, ISDN PRIs (ISDN: Integrated Services Digital Network; PRIs: Primary Rate Interface) were practically the only mode of communication available in the market for large business set ups. This technology was a much hyped one in past as it offered a communication circuit equivalent to 23 voice lines and also offered numerous DID (Direct Inward Dialing) numbers at a lower price as compared to the price incurred in 23 separate lines. This profit led to an enhanced sale of ISDN PRIs in past days.

SIP Trunks:

It has been a known fact that in future’s course, something is bound to replace the other.Time led to the development of VoIP (Voice over Internet Protocol) based communication. This technology began replacing ISDN and its deployment increased. SIP trunk is the latest development in the field of VoIP. One can hear this terminology in the communication sector quite often. Many Businesses world-wide, are depending on SIP Trunking as it is the best alternative available in the market which can bring more and more profits.

Which technology is the best choice for your business set up?

This decision depends on a number of factors:

  • The most important advantage of SIP Trunks over ISDN PRIs is that it not only offers every service that is offered by PRIs but also, unlike the PRIs, they do not confine you to 23 voice lines, thus bringing in cost saving. For example, if you only require 10 voice channels, you can go for them and if you require 40 voice channels, you can have them without paying any extra charge for a second PRI channel.
  • Unlike PRI circuit, SIP Trunks provide a more economic edge when it comes to both local and international calls. SIP offers very cheap calling rates. SIP Trunking does not restricts you to a particular phone exchange. You have freedom to go for a local number or choose phone numbers from different states.
  • Besides this, SIP Trunking is a technology built in a way that it can function with almost every phone system. ISDN PRIs usually need some kind of up-gradation whereas you can use SIP Trunks to replace the traditional phone lines without any major up-gradation.

The coin has two faces. SIP trunks may not necessarily prove to be a good option every time. For example, when a company compulsorily requires only 23 channels, ISDN PRIs may prove to be a better option.

  • You can purchase a bulk of DID numbers at a lower price with PRI services but doing the same with SIP Trunks will definitely charge you more as you will have to pay an additional amount for the 9-1-1 services.
  • The most serious disadvantage of SIP Trunking is that this service is highly dependent on the internet. When you do not have enough bandwidth or are dependent on a public internet connection which does not offer a quality service, you will experience a marked drop in calls and a poor voice quality thus having a negative impact on your customers.

So, which option is the perfect one for you? When you require a large number of voice channels and a very dependable voice quality, ISDN PRIs will suit you the best. When you do not require a plenty of DIDs and only need a few voice channels and have an access to a reliable internet connection, SIP Trunk will suit you the best. 

Viola Allen is a SIP expert and is currently employed with SIP Trunk Providers DotCom. Her passion is to write about the recent technological advancements, including Cloud Hosted PBX and SIP Trunking. Her main motive is to gain more and more information about the latest technological advancements in the industry.