ISO 20000 ITSMS certification: ISO 20000 is a global standard that describes the requirements for an information technology service management (ISM) system. ISO 20000 is a global standard that describes the requirements for an information technology service management (ITSM) system. ISO 20000 is comprised of two parts: a specification for IT Service Management (ISO 20000-1) and a code of practice for service management (ISO 20000-2).