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PSTN Replacement

PSTN closure: January 2027
BT Openreach is switching off the UK’s Public Switched Telephone Network by January 2027. This affects every analogue telephone line in the UK. Any device that connects to a PSTN line – lifts, alarms, fire panels, door entry, telecare – will stop working when that line is withdrawn.

What is the PSTN?

The Public Switched Telephone Network (PSTN) is the UK’s original copper wire telephone infrastructure. It has existed in various forms since the 19th century and has been the backbone of landline telephone communications for over 100 years. BT Openreach – the infrastructure arm of BT Group – operates the majority of the PSTN.

Openreach has confirmed the PSTN will be fully withdrawn by January 2027. This is part of a broader programme to migrate the UK’s telephone infrastructure to fully digital (IP-based) delivery. BT’s replacement service for residential users is called Digital Voice, delivered over fibre broadband.

Who is affected?

The PSTN closure does not just affect telephone calls. Many devices use PSTN lines for purposes other than voice conversations. The affected categories include:

Devices Affected by UK PSTN Closure

🛗 Lifts BS EN 81-28 emergency phone

🔔 Intruder Alarms PSTN diallers ARC signalling

🔥 Fire Panels Voice / digital communicators

❤️ Telecare / PERS Personal alarms lone worker devices

🚪 Door Entry Audio/video intercom systems

💳 PDQ / EPOS Older payment terminals

📟 Telemetry PSTN-connected monitoring units

☎️ PABX Systems Older business phone systems

Lift emergency phones – BS EN 81-28

BS EN 81-28:2018 (Safety rules for the construction and installation of lifts – Rescue of persons in stalled lifts) requires a two-way communication system capable of contacting a rescue service from the lift car. Most existing lift installations use an analogue PSTN line to deliver this.

When the PSTN line is withdrawn, the lift’s emergency communication system will fail. Lift owners and maintenance companies have three main options:

  • Install a broadband VoIP system on a new or existing fixed broadband connection at the site
  • Install a cellular VoLTE gateway with a VoLTE-provisioned SIM – the most practical option where no broadband exists or engineering access is difficult
  • Install a dual-path unit combining VoIP primary with VoLTE backup, providing resilience

Cellular VoLTE is frequently the preferred solution because it requires no fixed-line infrastructure, can be installed in existing lift shafts without significant cabling work, and provides a single SIM-managed connectivity path.

Intruder alarm diallers

NSI and SSAIB registered intruder alarm systems typically use a PSTN dialler to signal alarm activations to an Alarm Receiving Centre (ARC). These must be replaced or upgraded before January 2027. Options include IP signalling (Dualcom, CSL, etc.) or, where network connectivity is limited, a cellular voice path via VoLTE.

What specifiers and installers need to check

  • Audit every PSTN-connected device at the site before the 2027 deadline
  • For cellular VoLTE replacement: confirm the LTE module in the gateway supports VoLTE (IMS stack)
  • Source a SIM provisioned for IMS voice – not a standard data SIM
  • Verify LTE coverage at the installation point, particularly inside buildings and in basements
  • Test the end-to-end voice call before sign-off
  • Document the SIM, network, and device combination for maintenance records

VoLTE SIM for a PSTN replacement project?

Lift phones, alarm diallers, fire panels – we can source the right SIM product provisioned for IMS voice. Tell us the device and location.

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