The Public Switched Telephone Network - The public switched telephone network (PSTN) is the international network of circuit-switched telephones. Learn more about PSTN at HowStuffWorks. x
Black Belt Certification. The IASSC Certified Lean Six Sigma Black Belt (ICBB) is a professional who is well versed in the Lean Six Sigma Methodology, who leads improvement projects, typically in a full-time role. A Lean Six Sigma Black Belt possesses a thorough understanding of all aspects within the phases of D-M-A-I-C.
black belt - a black sash worn to show expert standards in the martial arts (judo or karate) badge - an emblem (a small piece of plastic or cloth or metal) that signifies your status (rank or membership or affiliation etc.); they checked everyone's badge before letting them in.