If your business still relies on a traditional phone line, alarm line, payment terminal or broadband service that runs over the old copper network, the PSTN switch off guide starts with one simple point: waiting creates risk. The UK’s legacy phone network is being retired, and businesses that leave decisions too late may face avoidable disruption, rushed replacements and gaps in service.
This change is often talked about as a phone system upgrade, but for many organisations it reaches further than desk handsets. It can affect lift emergency lines, door entry systems, EPOS devices, fax machines, care alarms, CCTV connections and broadband services that still depend on analogue infrastructure. That is why a sensible plan needs to look at the whole estate, not just the reception phone.
What the PSTN switch off guide means in practice
The Public Switched Telephone Network, or PSTN, is the old analogue phone network that has supported UK business communications for decades. It has been reliable for a long time, but it was built for a different era. As networks move to digital services, providers are retiring PSTN and ISDN lines in favour of IP-based connectivity.
In practical terms, that means voice calls and many related services will need to run over internet-based connections rather than traditional copper phone lines. For some businesses, the move is straightforward. For others, especially those with older equipment across multiple sites, there are more moving parts to manage.
The key point is this: the switch off is not just about replacing handsets. It is about making sure every service that depends on analogue connectivity is identified, tested and migrated properly.
Who is affected by the PSTN switch off?
Any UK business still using analogue or ISDN services is affected in some way. Small businesses may have only one or two lines to replace, while larger organisations may have complex phone systems, multiple numbers, call routing rules and connected devices spread across departments or locations.
Some sectors need extra care. Healthcare providers, legal firms, schools, estate agencies and logistics businesses often depend on continuous availability, clear call handling and specialist devices that are easy to overlook. If calls are central to client service, compliance or safeguarding, migration planning needs to be more thorough.
There is also an important difference between being affected and being at risk. A business may know the switch off is coming, but still be exposed if it has not checked non-voice services, resilience requirements or how its teams actually work day to day.
Why businesses get caught out
Most delays do not happen because people ignore the issue. They happen because the estate is larger than expected. A site survey starts with phone lines and quickly uncovers alarms, conferencing units, broadband dependencies and old devices that no one has reviewed in years.
The other common problem is assuming that a like-for-like replacement will solve everything. Sometimes it will. Sometimes it will not. A small office with a handful of users may move easily to hosted telephony. A larger operation with contact centre needs, call recording, Teams integration or hybrid working requirements may need a more tailored setup.
That is where a proper PSTN switch off guide helps. It turns a broad industry change into a manageable business project with clear actions and realistic timescales.
A practical PSTN switch off guide for your business
Start with an audit. You need a full picture of every service currently relying on PSTN or ISDN. That includes main phone lines, direct dial numbers, broadband circuits, alarms, payment devices, entry systems and any specialist equipment in plant rooms, lifts or remote sites. If you only review the obvious telecoms estate, you may miss the service that causes the real headache later.
Next, look at how your business uses communications. Do staff work from one site or several? Do they need mobile apps, voicemail to email, call reporting or CRM integration? Do customers expect calls to be answered in queues or routed by team, department or location? The best replacement is not always the closest match to the old setup. Often, this is the point where businesses realise they can improve resilience and flexibility at the same time.
After that, review connectivity. Digital voice services depend on a stable internet connection, so broadband performance matters. This is especially important if your current broadband is tied to the old phone network. In some cases, replacing telephony without improving connectivity only shifts the problem elsewhere.
Then plan number continuity. For most businesses, keeping existing phone numbers is essential. Number porting should be built into the migration plan early, with enough time for validation, scheduling and testing. If you leave it too late, you increase the chance of delays or temporary service issues.
Testing should never be treated as an optional extra. Before any final cutover, check call flows, hunt groups, voicemail, emergency calling, remote access and every third-party device being moved or replaced. If you have critical lines for customer service or safeguarding, staged testing is worth the time.
Finally, make sure staff know what is changing. Even a well-delivered migration can feel disruptive if users are unsure how to answer calls on a new device, transfer a call or access voicemail. Clear communication and light-touch training make a big difference.
What replacement options should you consider?
For many organisations, hosted VoIP is the most practical route. It removes dependence on legacy line infrastructure and gives businesses more flexibility across office, home and mobile working. It can also simplify administration and make it easier to scale as teams change.
Microsoft Teams telephony can be a strong fit for businesses already using Teams heavily for collaboration. It brings calling into a familiar workspace, although it is not automatically the right answer for every organisation. Businesses with more advanced call handling or sector-specific requirements may need a broader telephony solution alongside existing collaboration tools.
Some sites may also require analogue terminal adapters or specialist alternatives for devices that cannot move directly to IP. This is where the detail matters. A quick fix may keep a service live in the short term, but it is not always the best long-term option if reliability or compliance is at stake.
Risks to manage during migration
Downtime is the obvious concern, but it is not the only one. Power resilience matters because digital phone services do not behave in exactly the same way as traditional lines during power cuts. If your business has critical services, you may need battery backup, mobile failover or alternative continuity measures.
There is also the risk of partial migration. A business upgrades its main phone system but leaves alarms, lift lines or other legacy devices untouched until they fail. That tends to be more disruptive and more expensive in operational terms than dealing with the full picture from the start.
Supplier coordination can also slow projects down. If your telephony, broadband, IT support and building systems are all managed separately, responsibilities can become blurred. A joined-up migration plan reduces that risk.
When should you start?
Sooner than feels convenient. Not because every business needs to move tomorrow, but because good migrations take planning. If you have a simple setup, the process may be relatively quick. If you have multiple sites, specialist equipment, compliance requirements or internal approval steps, you will want more time.
Starting early also gives you options. You can assess what to keep, what to retire and what to improve, rather than making hurried choices under pressure. In our experience at RPS Telecom, the smoothest projects are the ones where businesses give themselves enough time to audit properly and test thoroughly.
How to make the change feel manageable
Treat the switch off as a business continuity project, not just a telecoms task. That mindset helps the right teams get involved early, from operations and IT to facilities and leadership. It also keeps the focus where it belongs: maintaining service, reducing risk and supporting the way your people actually work.
A good migration partner should explain the options clearly, flag any hidden dependencies and guide you through the practical decisions without overcomplicating them. Some businesses need a straightforward replacement. Others need a more phased approach. Neither is wrong. The right route depends on your systems, your users and how critical uninterrupted communication is to your operation.
The businesses that handle the PSTN switch off best are not necessarily the ones with the biggest budgets or the newest systems. They are the ones that ask the right questions early, check every dependency and build a plan around continuity. If your organisation starts there, the move away from legacy telephony becomes far less daunting and a lot more useful.
