Area Code 15 – Delft
The phone area code for Delft is 15 (international format +3115). Browse local exchange codes (NXX) and carrier assignments below.
📞 Exchange Codes (NXX) for Area Code 15
Select a central office code to view local carrier data and detailed information
📍 Geographic Location of Delft
Geographic Coverage and Administrative Jurisdiction
Country code +31 prefix 15 is a geographic National Destination Code (NDC) assigned to the city of Delft and its immediate surrounding areas in the province of South Holland, Netherlands. The numbering area encompasses the municipality of Delft, including the historic city center, the university district (TU Delft campus), and residential neighborhoods such as Voorhof, Buitenhof, and Tanthof. It also covers the nearby towns of Pijnacker-Nootdorp (partially) and the village of Schipluiden, which fall within the Delft telephony exchange region. This area code is administered under the Netherlands' national numbering plan, overseen by the Authority for Consumers and Markets (ACM).
Dialing Formats and Caller Instructions
For local callers within the Netherlands, the number is dialed as a national format: 015-XXXXXXX (where X represents the seven-digit subscriber number). When calling from abroad, the international format is +31 15 XXXXXXX, with the leading zero of the NDC omitted. For example, a typical Delft landline number would be +31 15 1234567. Callers from outside the Netherlands must replace the international access code with the plus sign (+) or their country's specific exit code (e.g., 011 from the US, 00 from most European countries).
Numbering Structure and Overlay Considerations
Dutch geographic numbers are fixed at nine digits in length, including the leading zero of the NDC. The subscriber number within the 15 area code is seven digits long. Currently, there is no overlay code in the Delft region; the 15 prefix remains the sole geographic code for this area. However, due to the increasing demand for numbers, the ACM periodically reviews numbering allocations. Businesses and residents in Delft may also have non-geographic numbers (e.g., 088 or 085) for corporate use, but these are not tied to the geographic area.
Technical Routing and Services
Geographic numbers in the Netherlands are traditionally associated with fixed-line PSTN and ISDN services. However, with the migration to VoIP and all-IP networks, many subscribers use their 015 numbers over broadband connections. Number portability allows users to retain their 015 number even if they move outside the geographic area, which can lead to a number no longer being strictly location-bound. For emergency services, calls made from 015 numbers are routed to the appropriate regional dispatch center based on the caller's physical location, not the area code. This ensures accurate emergency response.