The Public Switched Telephone Networks (PSTN) will be switched off in December 2025 by all telecom companies and will be replaced with an Internet Protocol (IP) digital network. Existing fax machines that are incompatible with new all IP digital networks will become obsolete and no longer capable of meeting Code Communications as prescribed in the REC. All communication methods referencing fax or facsimile will need to be removed and replaced with email (where this is not an existing option), unless an alternative form of communication is needed. Please note: The government have published preparatory guidance which includes migrating to IP-supported technology in advance of the planned decommissioning. UK transition from analogue to digital landlines - GOV.UK (www.gov.uk) Critical National Infrastructure (CNI) (“assets, facilities, systems, networks or processes and the essential workers that operate and facilitate them”) which is subdivided into 13 sectors including Energy, are advised to consider how they move to digital alternatives smoothly to avoid unnecessary interruption following the PSTN switch-off. Openreach's Energy Guidance Factsheet can be found in the CPs Accompanied Documents.