Area Code 237 – Oslo
The phone area code for Oslo is 237 (international format +47237). Browse local exchange codes (NXX) and carrier assignments below.
📞 Exchange Codes (NXX) for Area Code 237
Select a central office code to view local carrier data and detailed information
📍 Geographic Location of Oslo
Geographic Overview
The +47 237 prefix is a geographic number range allocated within the Oslo numbering area of Norway. As part of the national destination code (NDC) 23, this prefix serves the capital region, including central Oslo and its surrounding administrative districts. Subscribers assigned to this range are typically fixed-line services, though some numbers may be used for VoIP or other fixed-wireline services registered to Oslo addresses.
Dialing Formats
When calling a number that begins with +47 237 from abroad, you must dial the international access code (00 or +), followed by 47 (Norway's country calling code), then the 8-digit subscriber number that starts with 237. For example, a local Oslo number might appear as +47 237 45 678 in international format. Within Norway, you would dial the same 8-digit number without any trunk prefix, as Norway uses closed numbering plan: 237 45 678. There is no leading '0' to drop, and no area code is separate from the subscriber number.
Geographic Coverage and Jurisdiction
The 237 prefix is part of the Oslo numbering area, which historically covers the municipality of Oslo and parts of the former Akershus county. The Norwegian Communications Authority (Nkom) administers number allocations, and geographic numbers are tied to a fixed location. This means that the 237 range is associated with physical addresses in Oslo, and calls to these numbers are routed to the corresponding exchange or VoIP gateway registered to that area.
Caller Instructions
- Local callers (within Norway): Dial the 8-digit number directly, e.g., 237 45 678.
- International callers: Dial your country's exit code (e.g., 00 from most European countries, 011 from North America), then 47, then the 8-digit number: 00 47 237 45 678.
- Mobile callers within Norway: Same as local callers – no additional prefix is required.
Overlay and Number Portability
Norway does not use overlay codes for geographic numbering; instead, the entire country uses a single country code +47 with 8-digit subscriber numbers. Geographic prefixes like 237 are not strictly tied to a specific operator, as number portability allows subscribers to retain their numbers when changing providers. However, the geographic association remains for routing and emergency services purposes.
For businesses, having an Oslo 237 number establishes a local presence and can be important for customer trust. For individuals, it simply indicates that the line is registered in the capital region. Always verify the full number and its portability status when contacting a party, as the prefix alone does not guarantee the physical location of the line after porting.