A security technology refresh replaces equipment that is obsolete, unsupported or no longer meeting what the site needs. It is planned around end-of-support dates, parts availability and coverage gaps, and it usually runs as a phased migration so old and new hardware operate together for a period.
The deadline that matters is not the age of a device but the end of its firmware support. Unsupported equipment stops receiving security fixes, and spare parts become unobtainable at the worst moment.
Signals that a refresh is due
Repeated failures, unavailable replacements, recorders that cannot accept current cameras and firmware that no longer receives updates all point the same way. A coverage review may show the system no longer matches the building.
Phasing the work
Refresh the recording and network core first so new cameras have somewhere to connect, then replace field devices area by area. Keep the old system recording until the new one is verified.