Back in 2020, the telecoms industry was already setting out its long-term plan to retire the traditional PSTN and ISDN network in favour of all-IP telephony — a change that would eventually touch every business landline in the country.
For most organisations, the sensible response wasn't panic, it was planning: understanding which lines, alarm systems and payment terminals still relied on the old network, and building a migration path to VoIP well ahead of any deadline.
Note for readers today: exact switch-off dates have moved more than once since this post was written, so always check the current Openreach timetable — the underlying advice to plan early hasn't changed.