Main Page | See live article | Alphabetical index In telephony, a silent number (or an unlisted number) is a telephone number that is intentionally not listed in telephone books. Silent numbers often exist as certain telephone numbers can link to specific tests or control apparatus for the telephone network maintenance staff and are generally not for public use. Silent numbers are used for residential households as well, primarily for privacy and security concerns. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.