Area Code 231 – Dortmund
The phone area code for Dortmund is 231 (international format +49231). Browse local exchange codes (NXX) and carrier assignments below.
📞 Exchange Codes (NXX) for Area Code 231
Select a central office code to view local carrier data and detailed information
📍 Geographic Location of Dortmund
Geographic Overview
The area code 231 is a geographic National Destination Code (NDC) assigned to the city of Dortmund, located in the eastern part of the Ruhr metropolitan region in the state of North Rhine-Westphalia, Germany. It serves the city proper and several surrounding municipalities that have been incorporated into the Dortmund urban area. Key districts covered include Innenstadt, Hombruch, Hörde, Aplerbeck, Scharnhorst, and Eving, among others. The code is administered by the German Federal Network Agency (Bundesnetzagentur) and is used for fixed-line PSTN and VoIP services.
Dialing Formats
When calling a Dortmund number from within Germany, subscribers dial the national trunk prefix 0, followed by the area code and the local subscriber number. The local subscriber numbers in Dortmund are typically 7 digits long, resulting in a total national significant number length of 10 digits (excluding the leading 0). For example, a typical local number might be 0231 1234567. When dialed from abroad, the leading 0 is omitted, and the country code for Germany (+49) is used, resulting in the international format: +49 231 1234567.
Caller Instructions
- Local callers (within Dortmund): In most cases, you can dial the 7-digit subscriber number directly without the area code. However, for clarity and to avoid issues with mobile or VoIP networks, it is recommended to always use the full national format (0231...).
- National callers (from other German cities): Dial 0231 followed by the subscriber number. For example, from Munich, you would dial 0231 1234567.
- International callers: Dial your country's international access code (e.g., 011 from the US, 00 from most European countries), then 49, then 231, and the subscriber number. For example, from the UK, you would dial 00 49 231 1234567.
Overlay and Numbering Considerations
Dortmund does not have an overlay code; the 231 area code is the sole geographic code for the city. However, due to number portability, a number with the 231 prefix may be routed to a mobile or VoIP service, and conversely, a subscriber in Dortmund may have a number with a different area code. Always verify the actual location of the line if the call is for emergency services or location-based services.