Area Code 31 – Bertrange/Mamer/Munsbach/Strassen

Geographic Coverage and Administrative Context

The +352 31 prefix is a geographic National Destination Code (NDC) assigned to the south-central region of the Grand Duchy of Luxembourg, specifically serving the communes of Bertrange, Mamer, Munsbach, and Strassen. These localities form part of the canton of Luxembourg, situated to the west and east of the capital. The area is characterized by a mix of residential suburbs, commercial zones, and business parks, including the Mamer and Strassen industrial areas. Administratively, the code falls under the jurisdiction of the Institut Luxembourgeois de Régulation (ILR), the national regulatory authority for electronic communications.

Dialing Formats and Number Structure

In Luxembourg, the national significant number (NSN) length is 9 digits for all fixed and mobile services, including the leading '0' trunk prefix. However, for international dialing, the leading '0' is omitted. The +352 31 prefix is followed by a 6-digit subscriber number, resulting in a total of 9 digits when dialed locally (e.g., 31 12 34 56). For international callers, the format is +352 31 12 34 56. Local callers within Luxembourg must dial the full national number, including the trunk prefix '0' (e.g., 0 31 12 34 56). It is important to note that Luxembourg does not use area code-based local dialing; all calls within the country require the full national number.

Overlay and Numbering Plan Considerations

Luxembourg operates a closed numbering plan without geographic overlays. The NDC 31 is exclusively assigned to fixed-line services in the specified communes. Since the country's small size and high mobile penetration, fixed-line numbers are often used by businesses and households with traditional PSTN or VoIP connections. There are no known overlay codes for this region, and number portability allows subscribers to retain their numbers when changing operators, even if they move outside the original geographic area, though the NDC remains tied to the original service address.

Caller Instructions and Practical Examples

For local callers within Luxembourg, dial the full national number: 0 31 12 34 56. For callers from abroad, dial the international access code (e.g., 00 from most European countries, or + from mobile), followed by the country code and the national number without the leading '0': +352 31 12 34 56. When calling from a mobile phone, the same international format applies. It is advisable to confirm the subscriber number length, as some older numbers may have fewer digits, but all current allocations follow the 9-digit NSN rule. For VoIP users, the same dialing rules apply, ensuring compatibility with the public switched telephone network (PSTN).