Loss of a central office occurs when

• A. The PSAP building is destroyed
• B. The communications equipment located within the central office fails as a result of malfunction, water damage, fire within the central office, or other causes.
• C. End office linking to Tandem Router broken
• D. The Tandem Switch fails

Answer: (B)

A central office is the facility that houses the equipment responsible for processing and routing 911 calls for a PSAP. If the communications equipment inside that central office fails—whether due to malfunction, water damage, fire, or other internal causes—the central office can no longer perform its functions, so the site is effectively lost. This internal equipment failure directly disables the central office's operations, which is why that option best explains a loss of the central office.

External issues, such as a broken link from an end office to a Tandem Router or a Tandem Switch failure, involve equipment outside the central office and can cause outages, but they do not constitute the central office’s own equipment failing. A building being destroyed is also a catastrophic event, but the question focuses on the central office’s internal equipment failures as the defining cause.