Serial number

A serial number is a manufacturer-assigned unique identifier of a single device — as opposed to a model number, which identifies an entire product type.

A serial number answers "which device exactly", not "what kind". Without it, the workshop knows it is repairing a washing machine of a given model; with it, the workshop knows it is repairing the same washing machine for the third time this year.

It is easy to confuse with a case number. An RMA number identifies the ticket; a serial number identifies the thing. One device may pass through the workshop many times: each time with a new case number and the same serial number. Only putting the two together reveals equipment that keeps coming back, and separates a one-off fault from a defect running through a whole batch.

It also settles a more mundane question: whether a given unit is still under warranty. A purchase date is often impossible to reconstruct — the serial number is always on the device.

In Reklamator, serial numbers can be captured on tickets, so a service order can be tied to a specific unit rather than just a model. See how this works in service management.