Only ISO 17025 accredited providers can perform accredited quality assurance calibrations. The measuring equipment must be traceable to national standards, and measurement uncertainty stated. There are more stringent demands concerning the process, system, training of the technicians, and regularly performed audits. On the other hand, factory quality assurance calibration can be performed by non-accredited providers. This is often a simplified testing procedure, not necessarily traceable and based on national/international standards, and it does not include measurement uncertainties.