BT outlines UK PSTN retirement timeline and support for business customers

BT said the UK’s copper-based Public Switched Telephone Network is in its final phase of retirement, with an end-of-January 2027 target. The company framed the move as part of completing an All-IP transition that affects voice services still tied to PSTN.

BT said PSTN was designed for an Edge Resource Allocator (ERA) that no longer matches the requirements of modern organisations and critical national infrastructure providers. The company also said it had invested in nationwide full-fibre networks to support a shift away from analogue technology and enable all-IP connectivity.

According to the company, its full-fibre, fully digital networks are built for speed, resilience, and flexibility, and they support capabilities that legacy analogue systems cannot support. BT said it had migrated the majority of business customers off legacy platforms, and by January 2026 about 80% of its voice customers had moved to All-IP services.

BT said that as the deadline approached it carried out protective migrations where possible, automatically moving remaining analogue services to digital solutions to maintain continuity of key services. It also said protective migration was not suitable for every service or organisation, and that some customers needed to agree timings, test new solutions, or confirm how services were used. For lines that remained in place for Container Network Interface (CNI) customers after January 2027, BT said it planned to provide a limited voice service with basic voice calling functionality and described continued engagement as necessary. “We’re stepping in with protective migrations where we can, but we need customers to engage with us to ensure continuity of their services.”

BT said organisations were urged to make the move to digital, IP-based networks by January 2027 and that it would explain what would change, outline available options, and support customers moving to replacement technologies ahead of the deadline.