From 2020, businesses will no longer be able to buy any systems which use PSTN or ISDN technology. In 2025, BT is due to switch off both ISDN and PSTN services as it moves towards an entirely IP-based model of voice communication. What is the impact of this for your business and do you need to take any action before the ISDN switch off takes place?
What is PSTN?
The public switched telephone network (PSTN) is the term used to refer to all the world’s circuit-switched phone networks. PSTN uses copper cables to transmit voice calls and the fundamentals of the system have not changed for years. ISDN was introduced in 1986 to allow for both voice and data to be transmitted on a singular digital line.
What is ISDN?
Integrated Services Digital Network (ISDN) is a group of communication standards for digital connection and the transmission of voice and data over a digital line. ISDN is a circuit-switched telephone network system, but it also allows access to packet switched networks.

Why is ISDN being switched off?
In recent years there has been huge investment and a national roll out of super-fast fibre broadband, as well as a broad variety of new Ethernet alternatives which provide an improved service from previous ISDN and PSTN technology. BT stopped installing new ISDN within central London back in 2014, which gives some insight into how many organisations are moving away from ISDN.
However, there are still many companies that have not made the move and are still using ISDN lines. It is for this reason that BT have given such a long notice for the switchover.
What are the alternatives?
Due to huge investment in super-fast fibre broadband, there are alternatives widely available and affordable to all businesses. This means that IP communication technologies such as VoIP and Hosted Telephony are the most viable options for your business after ISDN switches off.
What is VoIP?
Voice over Internet Protocol (VoIP) is a cloud-based phone system which means all calls (incoming and outgoing) are sent over your broadband line. VoIP offers many more services than ISDN phone systems such as:
- Call Recording
- Call Queuing
- Unified Communications
- Voicemails saved and received over email
- Scalability
VoIP helps businesses become more efficient by enabling flexible work environments through hot-desking, home working and extending the service to mobile devices.
For more information on our Hosted VoIP service, please visit here or call us today to see how VoIP can benefit your business.
Why should you switch before 2025?
Although the switch off is scheduled for 2025, there will be gradual action taking place beforehand to make the switchover a little smoother. From 2020, businesses will no longer be able to add or make amendments to any existing systems they currently have as BT Group will not accept any new orders for products using PSTN or ISDN technology. There are many advantages to switching to VoIP and at iData we are ready to help you through the switchover process.
What are the advantages?
- Feature Rich – IP-solutions offer a broad range of features that were not available on ISDN networks. More control as in-built analytic systems which give you an insight on how the systems are working for you.
- Lower call costs – all the benefits of IP Telephony, including free site-to-site calls and lower call rates.
- Flexibility – Able to plug in and connect anywhere over a stable internet connection. Ability to relocate without having the hassle of installing any lines into your new office.
- Scalability – Option to reduce, add and change both channels and users when required.
- Resilience – Built in business continuity and disaster recovery with call re-routing.
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