In just under two years BT/Openreach will be switching off the Public Switch Telephone Network (PSTN) meaning that telephone landlines as we know them will no longer be operational.
This is going to require all phones to be replaced by internet-based voice services for telecommunications and more. Only a small percentage of businesses are aware of what this means for their daily operations, in spite of the fact that this is the biggest digital shift in communications since the switch to digital television.
This blog will look at the changes that are ahead and how to weather the storm for your business and its operations.
What is PSTN?
PSTN, sometimes referred to as the Plain Old Telephone System (POTS), is the telephone network to which all of our old landlines are connected, with many homes and businesses still using a landline that is connected to it. The wires strung overhead in the streets and the underground web of copper wires beneath the pavements, running to our houses and business properties are what make up this network.
However, this system, much of which has been in place since 1875, is aging and needing ever-increasing levels of maintenance and repair, which is making it no longer sustainable to continue to run. All of these reasons are what have led to BT/Openreach’s decision to switch the network off in December 2025.
What are ISDN and ADSL lines?
ISDN stands for Integrated Services Digital Network and Asymmetric Digital Subscriber Line (ADSL) is a similar concept. They use the old copper wires of the PSTN system to provide a broadband connection to homes and businesses. They use a digital transmission to provide voice and video calls, data and other network services through the circuits of the analogue PSTN wires. Introduced by BT in 1986, ISDN was able to offer digital features that a traditional landline telephone system couldn’t offer.
What are the 2025 PSTN and ISDN switch-off?
From December 2025, the PSTN network will be completely switched off meaning that all businesses and homes will need a digital internet-enabled phoneline to replace their telecommunication system. The switch-off has already begun to take effect with graduated steps having begun in 2020.
Salisbury and Mildenhall already had no PTSN-enabled services by May 2022, with a ‘stop-sell’ policy in place, with no PSTN packages available in these areas, and other towns and cities following. There should be a national ‘stop-sell’ in effect by September this year. The ultimate goal is to have Fibre to the Premises (FTTP) systems in place across the country with all companies and homes switching to Internet Protocol (IP) systems by the time the network is switched off.
The rest of the world is also making the change to IP systems and going fully digital, ahead of the UK are Germany, Japan and Sweden whilst Estonia and the Netherlands have already completely switched off their analogue systems
What can replace PSTN and ISDN for my company?
Companies need to replace their old phone and internet systems with Session Initiation Protocol (SIP) and Voice over Internet Protocol (VoIP) systems to guarantee a seamless switchover. VoIP is an internet-based replacement for the traditional landline. By turning the audio at one end of the connection into digital data packets, which are then transported over the internet to the other end of the connection where they are turned back into audio files, phone calls can be delivered over the internet. This means that phone calls can be made online almost instantly – similar to a mobile phone. We offer 3CX Phone Systems as a viable solution for this.
VoIP systems not only replicate all the same functions as a conventional landline system, but as they can be accessed from any internet-connected device, it allows businesses more flexibility to accept calls and connect to systems from anywhere, not just a dedicated location. SIP allows your company to communicate across various locations in several different multimedia formats, such as video, data and voice calls. This is perfect in today’s work-from-home, flexi-working approach that more and more companies are adopting.
What does the switch-off mean for my business?
Most businesses have a heavy reliance on the old PSTN and ISDN networks for their daily functions. Not only does the telephone line connect to it, but via the ISDN and ADSL connections many other systems have their function. Alarms, Electronic Point of Sale (EPOS) machines, door entry systems, CCTV and fax machines all use these networks.
Imagine the chaos when the PSTN is turned off if your company hasn’t made alternative provisions for these functions. There are solutions to help your business make the switch and the good news is that you don’t have to wait until 2025 to make these changes. There are also significant benefits to getting the process underway sooner rather than later.
What are the benefits of switching to an IP system?
Rather than leaving it to the last minute to get your business and home telecommunications switched over to a cloud-based phone system, there are a plethora of reasons for getting ahead of the curve and switching over sooner rather than later.
– Cost
Switching your phone system from PSTN to a cloud-based SIP system such as 3CX will save you money. No more line rental, and no maintenance or infrastructure costs with engineer callouts, and ultimately call charges will be part of your overall internet connection. So, the sooner you switch – the sooner you start to save.
– Flexible working
As previously mentioned, using a SIP system will allow your employees to connect, accept and make calls, voice or video, on any device and access systems and applications anywhere and anytime, which is perfect for flexi-working and work-from-home employees. Also, for your customer base, you can have a presence anywhere in the country, indeed the world, as numbers are no longer geographically based, which is perfect for companies with national and international reach.
– Future-proof your company
Not only preparing for the PSTN switch off and guaranteeing not a single day’s loss of connection, but a SIP system will be seamlessly able to expand as your company’s business grows. It also means that upgrades happen immediately and without the need for an engineer’s visit.
– Backup
Switching all of your communication systems and storage to a cloud-based system will mean that cyber security is easier to manage and should a site go down, a stand-by solution can be up and running in minutes and backups can be restored. You needn’t lose any communication or data.
Choose Eclarity for your telecommunications solutions
Eclarity is a company with decades of experience in supporting companies with their internet and telecommunication requirements. With national coverage and highly qualified engineers to design and support you with any of your internet and telecommunication issues, we are confident that we can help you find the perfect system for your needs. Why not join our ranks of satisfied clients today?
Get in touch by emailing or calling us on 01527908124 to discuss with a member of our friendly team your telecommunication switchover requirements.







