Overview
Germany has an open telephone numbering plan. There are 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.
The German telephone network uses 5200 geographical area codes, the length of which vary 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 are assigned to 01 and network services to 11:
Read more about this topic: Telephone Numbers In Germany