Telephone numbers in Germany
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. Overview. Germany has an open telephone numbering plan. There used to be no fixed lengths for either area codes or subscriber telephone numbers, meaning that some subscriber numbers may be as short as two digits. 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 phone number from a prefix or the digits already dialed. This feature allows the extension of the length of phone numbers without revoking or changing existing numbers. Cell phone numbers in Germany are not given geographic area codes but non-geographic codes. Thus they can easily be told apart from other numbers. A new numbering plan was introduced on 3 May 2010. Since then new landline phone numbers have a standard length of 11 digits, which includes the area code but omits the trunk prefix of 0. Area codes remain as  they are and are still variable in length. Exceptions to the 11 digit rule are the four cities of Berlin, Frankfurt, Hamburg and Munich, which are the only cities with two digit area codes and require only 10 digit numbers so as not to exceed the maximum length of 8 digits for a subscriber number. The German telephone network uses 5200 geographical area codes, the length of which varies from two to five digits (not including the trunk code 0), with five-digit area codes only being assigned in the New States (prefix 03). 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 and network services to 11. Geographic numbering. 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 same geographic area code. Originally, the first digits following the area code would indicate a smaller area within  these area codes or the type of the subscriber line (analogue or ISDN). However, this is no longer true as subscribers can keep their numbers when moving within an area code or when switching from analogue to ISDN. Further, new carriers assign numbers from different blocks. Non-geographic numbering. Non-geographic numbers were originally assigned the prefix 01. However, some of these services have been moved to other area codes. Emergency and network services. Network services are not dialed with the trunk prefix 0. They resemble local numbers that start with 11 but usually cannot be dialed after an  area code. History. Before German reunification, West Germany used country code +49 and East Germany used country code +37, each with its separate area codes and telephone networks. West Berlin was integrated into the West German telephone network, using the same +49 international dialling code as West Germany, with the area code 0311, later changed to 030. Unlike West Germany, from where calls to East Berlin were made using the prefix 00372 (international access code 00, East German country code 37, area code 2), calls from West Berlin required only the short code 0372. Conversely, those made to West Berlin  from East Berlin only required the short code 849. In 1992, two years after reunification, the phone networks were merged under country code +49. Geographic numbers in the New States were assigned area codes starting with 03, in some cases followed by the former East German area code (without the initial 0) or a code similar to it. Thus, Leipzig, for example, which had used East German domestic area code 041, was assigned the new area code 0341 in the unified telephone system. On the other hand, some area codes were changed: for example, the small town of Zossen used  to have East German area code 0323, but the new area code is 03377. Area code 030, formerly used by West Berlin, was assigned to the entire reunified Berlin. The released country code +37 was later reused as the initial digits of several new codes for European countries that became independent states at the time (e.g.: +370 for Lithuania, +374 for Armenia, +375 for Belarus, etc.), as well as some microstates whose telephone networks had formerly been integrated to those of surrounding larger countries (e.g. +376 for Andorra, +377 for Monaco and +378 for San Marino). The German phone network  became fully digitised in 1997, allowing more flexible use of the numbering space. On 1 January 1998, the Federal Network Agency (named the Regulatory Authority for Telecommunications and Postal Services at the time) became the numbering authority for phone numbers in Germany.