A quick guide to PSTN replacement services

How to / Guide

October 28, 2020

The phasing out of PSTN and ISDN services is not news to most, but for those yet to take the action to replace their voice services, the time is fast approaching to migrate to an alternative; namely VoIP in the form of SIP. Being able to offer PSTN replacement services in as many countries as possible is high on the priority list for most carriers and telephony providers, but what does it mean for customers?

What is a PSTN Replacement service?

In essence, when a provider says they offer full PSTN replacement, it means that they are able to provide a fully featured business telephony service in the specific country or region which includes, among other things, guaranteed CLI (Caller Line Identity), emergency call features and reachability to local services such as free phone numbers that are only available in region.

By using PSTN replacement services from an established SIP provider, customers negate the need to set-up and manage the local carrier arrangements themselves, which can be huge saving in management time, contractual agreements, additional technical infrastructure and all the costs that go with it.

In addition, using an established provider means you can benefit from a tried and tested infrastructure, often with built-in geo redundancy, security and resilience.


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What is involved in offering PSTN replacement services?

The answer to this question falls into two parts, the technical aspect and the contractual/ regulatory actions. The technical aspects are in most cases the easiest of the two to sort out. Focusing primarily on the physical interconnects, the process can involve local IP addresses, local hardware or data centers, and plenty of testing with local carriers.

The contractual and regulatory elements can be far more complex and time consuming. In most countries, and sometimes in different regions within a country, you will need a license from local regulators. These tend to come in two primary types – a provider or a reseller license. To get the license you will need to meet specific criteria unique to that country/region, which could include:

  • Having in country infrastructure
  • Undertaking regular audits and reporting usage and revenue
  • Having a local company
  • Adhering to local regulations and compliance directives, plus paying local taxes
  • Ensuring the carrier being used can offer the necessary services with the right SLAs

Obtaining a license can be relatively quick, but can just as easily take over a year, which is why providers might only provide full PSTN replacement services in certain countries.

What should you consider when selecting the right PSTN replacement?

Most enterprises have three basic needs when it comes to their telephony - security, reliability and quality of service. Beyond that there are four key questions you should ask your potential provider:

  • What are the specific services offered in each country?
  • What security, support and SLAs are offered across the service?
  • How are the services being delivered?
    • Are they using their own infrastructure?
    • Are there partners involved in the delivery process?
    • Do they have the necessary license and carrier agreements?
  • And of course, is it a cost-effective service?


Pure IP have a proactive program of maintaining and continually adding to the list of countries where we can offer full PSTN replacement services in order to provide the level of service our global customers demand. Our services are delivered using our own infrastructure and the licenses we hold are as a provider, simplifying the delivery process when it comes to SLAs, security and changes. It is what we have built our reputation on!

If you would like to understand more about PSTN replacement services or Pure IP, please get in touch.


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