Area Code 23 – Haarlem
The phone area code for Haarlem is 23 (international format +3123). Browse local exchange codes (NXX) and carrier assignments below.
📞 Exchange Codes (NXX) for Area Code 23
Select a central office code to view local carrier data and detailed information
📍 Geographic Location of Haarlem
Geographic Coverage and Administrative Jurisdiction
The +31 23 area code serves the city of Haarlem and its surrounding municipalities within the province of North Holland in the Netherlands. This includes key localities such as Bloemendaal, Heemstede, Zandvoort, and parts of the Haarlemmermeer polder. The code is allocated under the Netherlands' national numbering plan, which follows ITU-T E.164 recommendations. Haarlem is the capital of North Holland and lies approximately 20 kilometers west of Amsterdam, making it a significant urban center within the Randstad conurbation.
Dialing Formats and Caller Instructions
For callers within the Netherlands, the national trunk prefix '0' is used before the area code, resulting in the format 023 XXX XXXX for local calls. When dialing from abroad, the international access code (typically '00' or '+') is followed by the country code 31, the area code without the leading zero, and the subscriber number: +31 23 XXX XXXX. Local numbers within this area code consist of seven digits, with the first digit after the area code ranging from 2 to 9, excluding 0 and 1. It is important to note that the area code is mandatory for all calls within the Netherlands, even for local calls placed from within the same geographic region. This is due to the national numbering plan's structure, which requires full national number dialing for all calls.
Overlay and Numbering Plan Considerations
As of the latest updates, the 23 area code does not have an overlay code; it remains a single geographic code serving the Haarlem region. However, number portability is fully implemented in the Netherlands, allowing subscribers to retain their numbers when switching providers or relocating within the same geographic area. This means that a number with the 23 prefix may not necessarily be physically located in Haarlem, as it could be ported from another region. Despite this, the code retains its geographic significance for routing and administrative purposes.
Practical Usage and Examples
For a local business in Haarlem, a typical number might be 023 512 3456. To reach this number from the United States, a caller would dial 011 31 23 512 3456 (or +31 23 512 3456 from a mobile phone). From within the Netherlands, a caller in Amsterdam would dial 023 512 3456 as well, since the area code is required for all national calls. Understanding these dialing procedures ensures seamless connectivity for both domestic and international callers.