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.

Since then newly assigned landline telephone numbers have a standard length of eleven digits, including the area code.

Exceptions to the eleven-digit rule are the four cities of Berlin, Frankfurt, Hamburg, and Munich, which are the only cities with two-digit area codes and have ten-digit numbers to avoid exceeding the maximum length of eight digits for a subscriber number.

This is no longer true as subscribers can keep their numbers when moving within an area code or when switching from analogue to ISDN.

), 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 telephone network became fully digital in 1997, allowing more flexible use of the numbering space.