Telefonnummer

Telefonnummer, literally "telephone number" in German, is a numeric sequence used to address a telephone endpoint within a public switched telephone network. It enables routing of calls to fixed lines, mobile devices, or services, and is typically assigned to individuals, organizations, or businesses.

Internationally, numbers follow the ITU-T E.164 numbering plan. An E.164 number may contain up to 15 digits and consists of a country calling code, a national destination code, and a subscriber number. In international notation the number is written with a leading plus sign, for example [phone]; in domestic dialing, a trunk prefix or leading zero is often used, resulting in formats such as 030 12345678 in Germany.

National numbers vary in length; area codes and subscriber portions are country dependent. Mobile numbers may use distinct prefixes but generally follow the same overall structure.

Numbers can be allocated to people or organizations and are often portable between providers. Privacy and telecommunications regulations govern the use of numbers, with rules on unsolicited calls, data protection, and the designation of special service numbers (emergency, operator, premium-rate).

In German-speaking contexts, Telefonnummer covers both landline and mobile numbers and is used in Germany, Austria, Switzerland, and other communities. The international format is common in directories and online contact records.