Telecommunications

A core network in service for years runs on equipment whose vendor support has ended and whose configuration is documented nowhere. The field survey, device by device, capturing the actual configuration rather than the one on the original diagram, is what decides whether a migration succeeds. It is the gap between the two that produces cutover incidents.

The commercial constraint comes second. An operator tolerates no outage window longer than a few minutes, which imposes migrations in batches, carried out at night, with a fallback prepared and tested before each cutover. Rollout order is not a logistical convenience: handling the most exposed points first surfaces the real difficulties while there is still budget to respond to them.

Availability finally rests on equipment whose origin and update cycle must be known. Software supply-chain security is a component of network security here, not a separate subject.