The 2027 deadline is approaching
By the end of January 2027, the UK’s copper-based phone networks – PSTN (Public Switched Telephone Network) and ISDN (Integrated Services Digital Network) – will be permanently retired.
The plan was originally for the deadline to be at the end of 2025, but with over 2 million ISDN lines still reportedly live, BT and Openreach needed more time to ensure the infrastructure was in place, setting the new deadline of 31st January 2027.
From then on, all calls and connected services will rely on digital, internet-based alternatives. For SMEs still depending on analogue lines, the PSTN and ISDN switch-off represents both a risk and an opportunity.
Why the PSTN Switch Off matters for SMEs
Many small businesses assume their existing lines will continue working. Unfortunately, when the switch-off takes effect, any system using PSTN or ISDN will stop operating.
The impact could include:
- Missed calls and lost revenue – Customers unable to get through could easily turn to competitors.
- Operational disruption – Payment terminals, alarms, or fax lines may fail without warning.
- Compliance risks – Sectors such as legal, healthcare, and financial services could face GDPR, PCI, or patient confidentiality breaches.
- Weaker security – Analogue systems offer no protection against modern cyber threats.
Common business systems still relying on PSTN/ISDN
Our audits show that many SMEs are still exposed in ways they may not realise:
- Main business phone numbers – still running on copper.
- Alarms and fire/security systems – that use analogue dial-out.
- Card machines and payment terminals – in retail and hospitality.
- Lift and emergency call lines – critical for safety compliance.
- Fax machines – surprisingly common in medical and legal practices.
- CCTV and modems – tied to older analogue infrastructure.
These “hidden dependencies” can create serious disruption if left unchecked.
Business continuity risks beyond phones
The ISDN and PSTN Switch Off affects more than just phone calls. Businesses should also consider:
- Connectivity resilience – Do you have fibre broadband with 4G/5G failover?
- Disaster recovery readiness – How exposed would you be if your IT systems failed tomorrow?
- Cybersecurity – Is your business protected with MFA, secure backups, and endpoint security?
- Staff training – Are your people prepared to adopt VoIP and unified communications tools?
Preparing for the PSTN Switch Off: 5 key steps
1. Audit your infrastructure
- Catalogue all phone lines and devices using PSTN/ISDN.
- Check alarms, payment devices, lifts, and fax machines.
2. Assess continuity and risk
- Review failover internet connections, DR processes, and backup measures.
3. Plan your migration to VoIP
- Shortlist business VoIP providers.
- Allocate a migration budget.
- Define a realistic timeline before the 2027 deadline.
4. Upgrade to digital telephony
- Move to VoIP or UCaaS for cloud-hosted telephony.
- Strengthen connectivity with fibre, leased lines, and SD-WAN.
- Ensure secure-by-design systems with MFA, encryption, and device management.
5. Train your team
- Prepare staff for new VoIP features such as softphones, call routing, and IVR.
- Support adoption to minimise disruption.
Turning compliance into competitive advantage
Forward-thinking SMEs across South London are using the PSTN/ISDN Switch Off to:
- Modernise business communications – with flexible VoIP solutions.
- Improve customer service – with call queuing, routing, and callback features.
- Cut costs – by consolidating vendors and avoiding legacy line charges.
- Strengthen compliance – with Cyber Essentials, PCI, and GDPR-ready systems.
Palace Prime IT: Helping SMEs in South London prepare
At Palace Prime IT, we specialise in helping SMEs across South London navigate the PSTN and ISDN switch-off with confidence.
Our FREE PSTN/ISDN Audit gives you:
- A full map of your PSTN/ISDN dependencies (phones, alarms, lifts, payments, fax).
- A review of continuity, cybersecurity, and compliance risks.
- A tailored migration roadmap aligned with your budget and business goals.
Don’t leave it too late
The BT ISDN and PSTN switch-off is much closer than you think – consider all the time required to design and deploy your new future-proof technology. Businesses that act now will avoid disruption, reduce costs, and gain a modern, resilient IT environment.
Book your Free PSTN/ISDN Audit with Palace Prime IT today and future-proof your communications.