What Is PSTN and why is it being switched off?

The Public Switched Telephone Network (PSTN) is a legacy analogue system using copper wires for communication. While it has been essential for five decades, it’s clear that, in 2025, PSTN is outdated. The same can be said for Integrated Services Digital Network (ISDN), a 1986 upgrade that added features like improved voice and data transmission. With neither being able to meet modern demands, PSTN and ISDN are being replaced by digital IP technology.

Following “the big switch off”, digital technology will pave the way with enhanced speed, flexibility, and functionality.

Updated timeline for the PSTN switch off

2025 was the original date for the PSTN switch off. UK businesses and individuals, however, have seen BT extend this deadline from 2025 to 2027. The reason is to guarantee telecare users are fully supported during the transition. Telecare services – think emergency alarms and monitoring devices – often still rely on PSTN infrastructure. This delay supplies more time to adapt and upgrade to IP-based systems while protecting vulnerable users who depend on telecare solutions.

The PSTN switch off dates being reviewed showcases BT’s commitment to providing a smooth switchover with minimal disruption.

Timeline of PSTN service stoppage

The transition away from PSTN services follows a simple, clear timeline:

• September 2023: Sales of new PSTN services stopped. By stopping sales, this prevented further installations with this technology.
• December 2025: The initial deadline for the PSTN and ISDN switch off. UK residents would have needed to switch to IP-based networks by this date.
• January 2027: Revised – and final – deadline for the complete PSTN switch off. To remain operational, all services must transition to IP technology by this date.

Businesses and households are encouraged to plan to avoid connectivity disruptions for this digital future.

How will the switch off affect businesses?

The PSTN switch off will affect devices currently relying on analogue connections. These include:

• Alarms
• EPOS systems
• Door entry controls
• CCTV
• Fax machines

Without transitioning to IP-based systems, these products won’t just become obsolete – they’ll be unusable. Due to this, businesses must assess their systems and upgrade their connectivity solutions if necessary. Embracing IP technology also presents a pathway to opportunities. Benefits include enhanced communication, flexibility, and seamless integration with modern digital tools.

Transitioning to digital solutions: what Radius provides

It may have been delayed, but the PSTN and ISDN switch off date is still fast approaching. Radius is here with digital solutions to support businesses making the transition. Our key offerings include:

• Session Initiation Protocol (SIP) Trunk for seamless call handling.
• Cloud communications/VoIP for cost-effective, flexible communication.
• Full fibre broadband (FTTP) for lightning-fast speeds.
• Single Order Generic Ethernet Access (SOGEA) for simplified broadband without requiring a traditional phone line.

These technologies not only mean you’re ready for the PSTN and ISDN lines switch off. It also future-proofs connectivity while enhancing efficiency and scalability.

How Radius telecoms experts guide the transition

Our telecoms experts supply comprehensive support to guide businesses and stakeholders through the PSTN/ISDN switch off. This begins with our telecoms audit to identify affected products and services, where we then offer bespoke recommendations for upgrades. From communication infrastructure reviews to customising solutions, the audit helps businesses achieve these three goals: cost savings, improved efficiency, and enhanced security.

With strategic insights and expert guidance, Radius won’t leave you behind. Make the shift to digital technologies a seamless one.