RELATED RESEARCH TOPICS

1.
Telephone numbers in Germany
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The regulation of telephone numbers in Germany is the responsibility of the Federal Network Agency of the German government. The agency has a mandate to telecommunications in Germany and other infrastructure systems, Germany has an open telephone numbering plan. There used to be no fixed lengths for either area codes or subscriber telephone numbers, as a result, dialing sequences are generally of a variable length, except for some non-geographic area codes for which subscriber numbers use a fixed-length format. It is not possible to determine unambiguously the end of a number from a prefix or the digits already dialed. This feature allows the extension of the length of numbers without revoking or changing existing numbers. Cell phone numbers in Germany are not given geographic area codes, thus they can easily be told apart from other numbers. A new numbering plan was introduced on May 3,2010, since then new landline phone numbers have a standard length of 11 digits including the area code and omitting the trunk prefix 0. Area codes remain as they are and are variable in length. The German telephone network uses 5200 geographical area codes, the length of which varies from two to five digits, with area codes only being assigned in the New States. In general, geographic area codes start with digits 02 to 09, whereas other non-geographic area codes including those for cell phone usage are assigned to 01, geographic area codes have a length of two to five digits. The maximum total length is eleven digits, geographic numbers are assigned to carriers in blocks, from which these carriers can make derivative assignments to subscribers. Subscriber numbers do not start with 0 or 11 and can be called directly from landlines within the geographic area code. Originally, the first digits following the code would indicate a smaller area within these area codes or the type of the subscriber line. However, this is no longer true as subscribers can keep their numbers when moving within a code or when switching from analogue to ISDN. Further, new carriers assign numbers from different blocks, xxxx-xxxx This is the format used for the four largest geographic areas in Germany, Berlin, Hamburg, Frankfurt and Munich. Newly assigned numbers have a length of eight digits for the subscriber number. This is shorter than the maximum of eleven digits in other areas in order to avoid local numbers to be longer than eight digits, Numbers assigned in the past, which are generally grandfathered, may be as short as five digits. Xxxx-xxxx In area codes that use three digits, newly assigned numbers also have a length of eight digits, yielding a total length of eleven digits, grandfathered numbers may be as short as four digits