A calibration should be carried out by an ISO/IEC 17025 accredited lab. Sometimes in some specific context it is allowed to have the calibration done by:
- a lab that has standards traceable to ISO/IEC 17025 accredited calibrations
- the manufacturer
- the user of the instrument
There are no general requirements, each country has its own regulations and the extent to which it is an advice, recommendation or obligation also varies from country to country. The calibration must, at the very least, demonstrate compliance with the factory specifications of the device.
- International Organization for Standardization,"ISO/IEC 17025: 2017. General requirements for the competence of testing and calibration laboratories", 2017.