PSTN jargon: what your business needs to check
Understand the terms on your line inventory and supplier quotations before choosing a replacement.
November 2026 guidance: Openreach confirms PSTN closure on 31 January 2027. Your communications provider sets your migration date; not every analogue service retires together. Confirm the arrangements for each line.
- PSTN
- Public Switched Telephone Network: the legacy telephone network. Openreach's closure is separate from retiring every copper broadband connection.
- ISDN
- Integrated Services Digital Network: legacy digital telephone lines commonly connected to business PBXs. Ask your provider about replacing the service, not just the handsets.
- WLR
- Wholesale Line Rental: a wholesale service behind many traditional lines. Ask whether your voice or broadband contract has a WLR dependency.
- SoGEA
- Single Order Generic Ethernet Access: broadband without a traditional analogue voice service, generally using copper for the final connection. Calling requires a separate digital service.
- FTTP
- Fibre to the Premises: fibre reaches the building. Availability, upload speeds and installation arrangements depend on the chosen service; it does not automatically include phone calls.
- FTTC
- Fibre to the Cabinet: fibre reaches a street cabinet and copper completes the connection. Check whether your specific service depends on WLR; FTTC is not full fibre.
- ATA
- Analogue Telephone Adapter: connects some analogue equipment to an IP service. It does not establish compatibility or certify alarm, lift, telecare or fax operation.
- SIP trunk
- An IP connection between a compatible PBX and a calling provider. Check supported hardware, licences, concurrent-call capacity and emergency calling.
- PBX
- Private Branch Exchange: the system that routes an organisation's calls. Its maintainer should confirm whether it can be retained with supported SIP connectivity.
- VoIP
- Voice over Internet Protocol: calls carried as data. It can be delivered through a hosted phone system or an on-site PBX; connectivity and power arrangements matter.
- EVAc
- Openreach's temporary emergency voice access service for eligible unmigrated lines after closure. It cannot be ordered in advance, capacity cannot be reserved and linked broadband retention is not assured.
- UPS
- Uninterruptible Power Supply: battery backup for specified equipment. Check the router, network, phones and devices together, including tested runtime and maintenance.
- 4G fallback
- An alternative mobile data connection when the main circuit fails. Coverage, failover equipment and power must be checked; it is not automatic protection for every connected device.
- Telecare
- Care alarms and monitoring devices used to summon assistance. The responsible service provider must confirm a supported migration path and test it, including during power loss.
Official sources and scope
- Openreach: deadline and temporary safeguards, 24 September 2026
- GOV.UK: UK transition from analogue to digital landlines
- GOV.UK: moving landlines to digital technologies
Planning guidance, not a quotation or safety certification. Communications and equipment providers must confirm current terms, dates, compatibility and testing for your services.