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Voice over Internet Protocol

Asked by Vikki SladeLiberal DemocratDepartment for Science, Innovation and TechnologyTabled Answered 4 June 2026UIN 5481

The question

To ask the Secretary of State for Science, Innovation and Technology, what data her Department holds the percentage of landline telephone connections that have been migrated from the Public Switched Telephone Network to digital voice services.

Answered by Kanishka Narayan

The analogue Public Switched Telephone Network (PSTN) is a privately-owned telecoms network and the decision to upgrade it to digital Voice over Internet Protocol (VoIP) was taken by the telecoms industry in 2017.

Over 92% of PSTN landlines have already been migrated to VoIP. As of 31 March 2026, fewer than 2.8 million PSTN lines remain operational, down from 35.2 million PSTN lines at the network’s peak.

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