ISDN Replacement – The situation!

ISDN Replacement

In August 2015 BT’s Group CEO finally put an end to the speculation about the future of BT’s ISDN service. Gavin Patterson announced that the Public Switched Network Service (PSTN) in 2025. Whilst 2025 seems like a long way off forward thinking businesses are already weighing up the alternatives; very wise in the light of the fact that BT will no longer but accepting orders for or amendments to ISDN products and services from 2020.

VoIP technology has been available for fifteen years and there has been a steady migration of business users across to VoIP alterative solutions but this announcement represents a fundamental change in that the 30 million ISDN users will need to look for an alternative sooner rather than later. So, what are the choices?

SIP Trunking

Similar to traditional ISDN, you will have a phone system on site but will route your calls through the Internet via SIP trunks. SIP trunks may prove to be more effective than a hosted or virtual solution for larger enterprises with lots of users. The first step is to review your current service and see how it is likely to measure up against your future requirements. If you have an on-site IT resource who can manage the system and if local control is crucial to your business then you should consider replacing your legacy phone system with a SIP enabled IP-PBX. When looking for a SIP provider it’s a good idea to consider one that can support a mobile workforce and includes call security options.


Also referred to as Cloud telephony or Unified Communications as a Service, hosted solutions are popular choices for modern businesses who do not want to purchase and maintain a phone system in-house. With hosted the system resides in a data centre and your service provider takes responsibility for owning, configuring and managing the system. If you want access to IVR, voicemail, ring groups and other corporate features but prefer a monthly subscription model rather than shelling out for an expensive phone system then hosted may be for you.


We are often asked if it is possible to combine a legacy or standard phone system with a VoIP system. It is possible to cease the ISDN circuit and replace it with an ISDN to SIP Gateway adapter allowing the business to keep their current system and integrate with a VoIP solution to get the basic benefits without a full upgrade. Hybrid systems are a good choice for growing businesses who want to take the first step towards filling the gap between old technology and the cloud systems of tomorrow whilst keeping upgrade costs to a minimum.

Firstcom are experts in designing ISDN replacement solutions for businesses and are leading the way in Germany where migration from ISDN is already underway.

Book a virtual meeting!

We can give you a tour of our amazing system and how it can benefit you!

[contact-form-7 404 "Not Found"]

This is a unique website which will require a more modern browser to work!

Please upgrade today!

Firstcom Europe