Visit our COVID-19 information page (Opens in new window) for the latest information regarding health and safety practices, requirements for entry, and any geographic-specific impacts.
To schedule, reschedule or cancel an exam:
We encourage you to schedule/purchase your exam online. Get started by logging in to your web account on the Certified Mission Critical Operator (CMCO) website. If you have any trouble, contact us or see our frequently asked questions.
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Monday–Friday, 7:00 a.m.–7:00 p.m. CT; closed on local holidays.
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Toll-free customer service numbers are available in the following countries. If your country is not listed, please use the toll number at the bottom of this section.
9:00–18:00 CET (8:00–17:00 GMT) Monday–Friday; closed on local holidays.