Area Code 42 – Plateau de Kirchberg

Geographic Overview

The +352 42 numbering range is a geographic allocation assigned to the Plateau de Kirchberg area in Luxembourg City. This district, situated in the northeastern part of the capital, is a major administrative and financial hub, hosting numerous European Union institutions, banks, and corporate headquarters. The code serves both residential and business subscribers within this specific urban zone.

Dialing Formats

When calling a number in the +352 42 range from abroad, the international format is used: +352 42 XX XX XX (or +352 42 XXX XXX, depending on the exact subscriber number length). From within Luxembourg, callers must dial the national significant number, which includes the area code: 42 XX XX XX. For local calls within the same geographic area, the full national number is still required, as Luxembourg uses a closed dialing plan where the area code is an integral part of the subscriber number.

Numbering and Overlays

Luxembourg's national numbering plan, administered by the Institut Luxembourgeois de Régulation (ILR), follows ITU-T E.164 recommendations. Geographic numbers are typically eight digits long, including the leading '4' of the area code. The 42 prefix is not overlaid; it is uniquely assigned to the Plateau de Kirchberg. However, number portability allows subscribers to retain their 42 numbers when moving to other geographic areas or switching to VoIP services, though this may affect the geographic significance of the prefix.

Caller Instructions

• International callers: Dial the international access prefix (e.g., 00 from most countries, or + from mobile), followed by 352 (Luxembourg's country code), then the 42 area code and the subscriber number. Example: +352 42 123 456.
• Domestic callers: Dial the eight-digit national number directly, e.g., 42 123 456. No trunk prefix is used in Luxembourg.
• Local callers: Even within the Plateau de Kirchberg, dial the full national number as there are no local dialing shortcuts.

Regulatory and Technical Notes

Geographic numbers like those in the 42 range are primarily used for fixed-line PSTN and VoIP services. They are subject to ILR regulations regarding tariff transparency and emergency services access. Callers should be aware that while the 42 prefix indicates a geographic location, number portability means the actual physical location of the called party may differ. For emergency calls, the European emergency number 112 is always available, regardless of the dialed prefix.