Area Code 2133 – Oslo

Overview of Area Code 2133

Area code 2133 is a geographic prefix assigned to the central part of Oslo, the capital city of Norway. It forms part of the national destination code (NDC) structure under the country calling code +47. In the Norwegian numbering plan, geographic area codes are not separated from the subscriber number by a trunk prefix like '0' as in some other countries; instead, the full national significant number (NSN) is dialed directly. For Oslo, the NDC is 21, and the local subscriber number begins with 33, making the complete national number 21 33 xx xxx.

The 21 prefix is one of several geographic codes serving the Oslo metropolitan area, alongside 22, 23, and 24. These codes are allocated by the Norwegian Communications Authority (Nkom) to fixed-line operators and are used for both traditional PSTN and VoIP-based fixed services. The 2133 range is specifically used for numbers in the central business and residential districts of Oslo, including areas such as Sentrum, Grünerløkka, and Majorstuen, though the exact allocation may vary among operators.

Dialing Formats

When calling a number with area code 2133 from within Norway, you must dial the full 8-digit subscriber number, which includes the area code. For example, if the subscriber number is 33 45 67 89, you would dial 21 33 45 67 89. There is no trunk prefix to omit; the number is dialed as a continuous sequence of eight digits.

From outside Norway, you need to dial the international access code (00 or +), followed by the country code 47, and then the 8-digit national number. For instance, to call the same number from abroad, you would dial +47 21 33 45 67 89. Note that the leading '21' is part of the national number and must be included after the country code.

Caller Instructions

For local callers within Oslo, dialing the 8-digit number is sufficient. For callers elsewhere in Norway, the same 8-digit number is used; there is no area code prefix to add or remove. For international callers, always include the +47 country code. It is important to note that numbers beginning with 21 are not mobile numbers; they are fixed-line or VoIP-based geographic numbers. Therefore, they are typically charged at standard fixed-line rates, which may be lower than mobile rates.

If you are calling from a mobile phone in Norway, you can dial the number directly. However, be aware that some mobile operators may require you to include the area code even for local calls, but in Norway, the full 8-digit number is always required.

Overlay and Number Portability

Oslo does not have an overlay code; the 21, 22, 23, and 24 codes coexist as separate NDCs. Number portability is available, meaning that a number with the 2133 prefix may be assigned to a different operator than the one that originally owned the range. This does not affect the geographic significance of the number; it remains associated with Oslo for routing and emergency services purposes.

For businesses, having a 2133 number can establish a local presence in Oslo, which is beneficial for customer trust and local marketing. VoIP providers often offer these numbers to companies that want a virtual presence in the capital without physical offices.