Area Code 2138 – Oslo
The phone area code for Oslo is 2138 (international format +472138). Browse local exchange codes (NXX) and carrier assignments below.
📞 Exchange Codes (NXX) for Area Code 2138
Select a central office code to view local carrier data and detailed information
📍 Geographic Location of Oslo
Geographic Overview
The prefix +47 2138 is a geographic National Destination Code (NDC) assigned to the capital region of Oslo, Norway. As part of the Norwegian numbering plan administered by the Norwegian Communications Authority (Nkom), this code falls within the 21-XX range reserved for fixed-line services in the Oslo metropolitan area. The coverage area includes the central business district, surrounding boroughs, and key administrative zones, serving both residential and commercial subscribers.
Dialing Format and Usage
When calling a number with the prefix 2138 from within Norway, subscribers must dial the eight-digit local number in the format 21 38 XX XX (without the leading trunk prefix '0', as Norway uses closed numbering with no trunk code). For international callers, the full E.164 format is +47 21 38 XX XX, where +47 is the country calling code for Norway. This format ensures correct routing through international gateways.
Administrative and Regulatory Context
Oslo's numbering resources are managed under the national numbering plan, which allocates geographic codes based on historical telephony regions. The 21-XX range is specifically designated for the capital, distinct from other Norwegian geographic codes such as 22 (also Oslo) or 5x (Western Norway). This prefix is used exclusively for fixed-line services, including traditional PSTN and VoIP-based fixed connections, but it is not assigned to mobile networks. Mobile numbers in Norway always begin with 4, 9, or 58-59.
Caller Instructions
For local callers within Oslo, dialing the eight-digit number directly is sufficient. For callers from other Norwegian regions, the same eight-digit format applies, as Norway does not require area codes for domestic calls. International callers must replace the leading '+' with their country's international access code (e.g., 00 from most European countries, 011 from North America) followed by 47 and the subscriber number. Always verify the complete number, as omitting the final digits can result in misdialing.
Businesses and residents using this prefix benefit from the stability of geographic numbering, which can enhance local trust and facilitate emergency services location identification. However, with the rise of number portability, a 2138 number may be routed to a VoIP provider or a different physical location, so callers should not assume a fixed geographic tie solely based on the prefix.