The withdrawal of the UK’s Public Switched Telephone Network (PSTN) and ISDN services in January 2027 creates a non-negotiable deadline for infrastructure change, if required. Unlike many gradual technology upgrades, this is a fixed transition point driven by telecom providers, not airport operators. After next January, systems that depend on copper-based connectivity will lose their underlying support, requiring migration to IP-based alternatives within defined timeframes.
For airports, this is not limited to administrative telephony. Many operational systems, including some air traffic control radio communication interfaces, rely on the same legacy infrastructure. The switch-off therefore has direct implications for safety-critical communications. .
The Scope Of Impact: Systems Still Dependent On Legacy Connectivity
Many airport systems were designed around stable, circuit-switched connections. These systems often operate in the background, making their dependency on PSTN or ISDN less visible until service withdrawal becomes imminent.
The impact of the PSTN switchoff and ISDN switchoff extends across multiple operational areas, including:
- ATC voice communication systems and radio interfaces
- Crash phone and emergency communication lines
- Emergency Voice Communication Systems (EVCS)
- Security and alarm systems
- Ground-to-air communication links supported by analogue circuits
Unfortunately, these systems are not interchangeable with standard IT services, but are integrated into operational workflows and require predictable performance under all conditions.
What Are The Operational Risks And Consequences Of Inaction?
Failure to address the PSTN switchoff could bring a range of both technical and operational risks. As services are withdrawn, systems dependent on legacy connectivity may experience degraded performance or even complete loss of functionality.
This is especially worrying for ATC environments, where communication reliability is directly linked to safety. Any interruption to voice systems, emergency lines, or radio connectivity could introduce unacceptable operational exposure. Even partial degradation, such as increased latency or reduced signal integrity, can affect coordination between controllers, pilots, and ground services.
There is also a compliance dimension. Airports must demonstrate that their communication systems meet regulatory and safety requirements. Continuing to rely on unsupported infrastructure makes this increasingly difficult to justify.
From Copper To IP-Based Communication
The transition required is not simply a change in service provider, but a fundamental shift in how communication systems are delivered. Copper-based, circuit-switched connectivity is being replaced by IP and fibre-based networks capable of supporting voice and signalling in a different format.
In aviation environments, the transition process typically involves:
- Moving voice communication systems onto IP networks
- Supporting both digital and existing analogue equipment during transition
- Ensuring compatibility with established aviation communication standards
- Maintaining deterministic performance characteristics expected in ATC operations
Cloud-based and distributed communication architectures are becoming more relevant as part of this shift, allowing systems to be managed centrally while supporting remote or multi-site operations – provided that underlying network performance is controlled.
Practical Considerations For Planning And Implementation
Air traffic control radio communications operators must approach this transition as an infrastructure programme rather than a simple upgrade. The timeline is externally defined, but implementation must be aligned with individual operational constraints.
Important considerations include:
- Identifying all systems dependent on PSTN or ISDN connectivity
- Assessing which components can be retained and which require replacement
- Defining a phased migration plan to avoid service interruption
- Testing communication performance under operational conditions
- Coordinating changes with regulatory and safety requirements
To avoid disruption, integration will be required across multiple system types. This will include voice communication control systems, radio interfaces, and emergency communication infrastructure. Engineering-led solutions can support this transition by enabling interoperability between your existing equipment and new network environments. This may involve the use of standards-compliant voice systems, interface modules for legacy equipment, and communication platforms designed for aviation use. The objective is not simply to replace your old infrastructure, but to maintain operational continuity while adapting to new network requirements.
Find Out More
With the 2027 PSTN and ISDN switchoff approaching fast, an early assessment of your communication system dependencies is essential. Copperchase supports airports to identify their risk exposure and implement compliant, IP-based communication architectures that align with their operational timelines and safety requirements. Please get in touch to find out more.
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