The digital upgrade

What you need to know about the ISDN switch off

Posted by Casey Solomon

Integrated Services Digital Network (ISDN) is the circuit-switched  telephone network that transmits voice, data, video and other network services via the digitalised circuits of the Public Switched Telephone Network (PTSN). By 2025, PSTN circuits will be turned off indefinitely.Legacy landlines are quickly becoming antiquated as we move further into the digital age. Driven by the rising cost of maintaining PSTN/ISDN equipment and the attractive convenience offered by VoIP (Voice over Internet Protocol) solutions, telecom operators are pulling the plug on outdated telephony for good. The UK VoIP market is expected to grow by $4.83 billion from 2022 to 2026, with a CAGR of 9.08% as businesses and individuals open their eyes to the myriad benefits of digital telephony. With the BT ISDN switch off drawing closer, it’s important to understand what this means and why it’s time to shift your business communications to a modern phone system to future proof your company.

What is the ISDN switch off

The copper-based PSTN and ISDN network will be turned off entirely by 2025. The process began in 2020, and will continue over the next few years as the world shifts to fully digital networks. The switch-off will affect both business and home phone lines, also impacting other non-voice services connected to PSTN or ISDN lines such as alarms, CCTV systems and EPOS machines. This means that existing hardware and infrastructure that relies on this technology will no longer function. Instead, you'll need handsets that can use internet protocol (IP) technology to transmit voice in a digital format using a broadband connection when you make or receive a phone call.

Why is ISDN being switched off

The short answer is that ISDN is being switched off because it's simply too old and outdated to maintain modern business communications. PSTN is the copper wire-based telephone network which has remained basically unchanged since the hey-day of public telephone networks. ISDN is a digital platform that came into use in the 1980s. At the time, it provided a vastly improved service that allowed users to transmit not only voice data, but video and other data as well. A lot has happened since the 1980s, and today neither ISDN or PSTN technologies are capable of handling and delivering the volume or quality of data required in today’s increasingly digital and hyper-connected world.

What are the key dates for the ISDN switch off?

As it stands, the plan is to stop installing or adding ISDN lines in the UK in 2023, and this is already in motion. Many areas with high-level coverage with gigabit-capable networks have initiated the process of leaving the ISDN network behind. The aim is for the ISDN phase out to be completed by the end of December 2025. After this, there will be no more traditional copper lines in use for voice and data transmission.

What is the risk of the ISDN switch off or WLR withdrawal?

The main risk of the BT Openreach withdrawal of Openreach wholesale line rental (WLR withdrawal) and ISDN switch off is for those businesses who don’t transition to VoIP-based systems in time. As soon as possible, it’s time for businesses to review their communications infrastructure and start making the necessary preparations to switch to VoIP. If, come December 2025, you’re not fully prepared and running your communications on a digital network, you will run into problems, added expenses and missed opportunities if you’re left behind with a redundant system.

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What is ISDN going to be replaced with?

All ISDN lines will be replaced by digital phone lines that route calls using IP technology. As people embrace mobile and internet communications, traditional ISDN line technologies aren’t capable of meeting current increasing demands. IP allows for the transmission of data via the internet, which makes it a much more convenient, accessible and affordable solution for both business and personal use.

What are the alternative options to ISDN?

Everyone will need to upgrade their traditional telephone system to an internet-based or hosted VoIP phone system. This can be to a system that supports Session Initiation Protocol (SIP) trunks that allow you to make calls using a data connection (think of it as an in-between solution) or shifting your communications to a fully hosted cloud system for increased flexibility.

Will Openreach provide the PSTN replacement products and services?

As we move closer to the BT ISDN switch off, Openreach products will be offered as a Single Order variant of ADSL or Fibre broadband services. These new services will require you to invest in the necessary equipment and a communications provider such as bOnline. Typically, VoIP phone systems are available on a monthly or yearly payment plan, and as they function using the internet, they’re much more affordable and require less maintenance than traditional lines. What other lines and calls services are impacted by the 2025 closure?The PSTN supports WLR, ISDN2 and ISDN30, Local Loop Unbundling Shared Metallic Path Facilities (LLUSMPF), Narrowband Line Share and Classic Products. If you’re still relying on these lines and call services, it’s time to upgrade for the 2025 closure. If you're unsure if you use any of these, it pays to check with your current communications provider.

What other lines and calls services are impacted by the 2025 closure?

The PSTN supports WLR, ISDN2 and ISDN30, Local Loop Unbundling Shared Metallic Path Facilities (LLUSMPF), Narrowband Line Share and Classic Products. If you’re still relying on these lines and call services, it’s time to upgrade for the 2025 closure. If you're unsure if you use any of these, it pays to check with your current communications provider.


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Things to consider before the ISDN switch off

BT is no longer accepting new ISDN orders. Before the switch off, it’s important to consider upgrading to VoIP or moving to a fully hosted PBX system. For small businesses that want to reduce maintenance and IT staff time, the latter is a great option to lower upfront costs.  Although the switch-off date is drawing closer, there’s no need to panic. You still have plenty of time to figure out what you need to do and set a roadmap for achieving it before December 2025. Be sure to do your research to find a VoIP service provider that meets your business needs and sits well with your budget.

What does your business need to do ahead of the ISDN switch off?

If you’ve decided to transfer your existing phone system to a VoIP system or hosted cloud network, the process is quite straightforward. Suppliers will take care of most of the groundwork for you, and many SIP trunk providers will be able to upgrade your current system, so you won’t have to worry about investing in a completely new solution. This involves transferring your existing business numbers. You’ll also need to make sure that your internet connection offers enough bandwidth to handle your new network.

What questions should you be asking about the ISDN switch off?

You need to ask yourself which kind of system you want to upgrade to. VoIP solutions and cloud PBX have different benefits depending on your business needs. Do your research to figure out which one is going to be most effective for your business communications. It’s also important to consider which additional VoIP features and functionalities you want from your new phone system, as this can make a huge difference to how you communicate internally and your customer service.

How do you start the process of switching from ISDN to VoIP?

First of all, outline your business needs and the key features you expect from your new phone system. Next, do your research to evaluate potential providers to see which one best suits your needs. If you’re a small or growing business, you can easily get in touch with bOnline to hear more information about our plans and benefits to help you make this important decision. There are also some key things you need to check when moving to VoIP. For instance, you’ll need to ensure your internet connection is strong enough and that the provider offers a Quality of Service commitment to ensure great audio quality and uptime. If you’re transferring your existing phone line, be sure to check whether it supports VoIP. Most modern phone systems do, but it always pays to be sure.