One of the main features of the hard wired—and now fibered--telephone system has been its reliability. The reason for its reliability is a relatively simple one: the phone companies, starting with Bell Telephone, have set very high quality standards for themselves and their vendors. Adherence to high quality standards is even more important today, given society’s increasing dependence on telecommunications. Paradoxically, rapid technological advances in fiber-optic component technology and material science have made it difficult for reliability methodologies to properly quantify the reliability of components before they are placed in service. To get around this difficulty, in the choice of products and vendors, most suppliers and end-users rely heavily on qualification tests. In the case of immature technologies, however, qualification tests alone cannot guarantee reliability. True reliability programs must be used to follow up on them and verify their results.