Area Code 2428 – Oslo

Overview of Area Code 2428

Area code 2428 is a geographic subscriber number range within the Norwegian public switched telephone network (PSTN), allocated to the capital region of Oslo. As part of the national numbering plan administered by the Norwegian Communications Authority (Nkom) under ITU-T E.164, the prefix 2428 is not a standalone area code but rather a central office code within the larger Oslo numbering area. The full national significant number (NSN) for subscribers in this range is eight digits long, beginning with the digits 24, followed by the four-digit exchange code 28, and then a four-digit subscriber number. Thus, a complete domestic number appears as 2428 XXXX, while the international format, including Norway's country calling code +47, is +47 2428 XXXX.

Geographic Coverage and Jurisdiction

The 2428 prefix serves the central and surrounding districts of Oslo, Norway's capital and most populous city. Oslo is both a municipality and a county, and its administrative jurisdiction encompasses numerous boroughs, including Sentrum, Frogner, St. Hanshaugen, Grünerløkka, Gamle Oslo, and others. Numbers with the 2428 prefix are typically assigned to businesses and residents within these urban areas, reflecting the dense telecommunications infrastructure of the city. Because Norway employs a closed numbering plan, there are no separate trunk prefixes or area codes for different parts of Oslo; all geographic numbers share the +47 country code and an eight-digit NSN.

Dialing Formats and Caller Instructions

For local callers within Norway, dialing a 2428 number requires only the eight-digit subscriber number: 2428 XXXX. There is no need to dial a trunk prefix such as '0' because Norway uses a closed numbering plan. For international callers, the correct format is the international access prefix (typically 00 or +), followed by Norway's country code 47, and then the eight-digit subscriber number. For example, to call a number in Oslo with the prefix 2428, an international caller would dial +47 2428 XXXX. It is important to note that the leading '24' is part of the geographic numbering range for Oslo and is not a separate area code; therefore, callers should not drop or alter any digits when dialing from abroad.

Overlay and Numbering Considerations

Oslo has not implemented overlay area codes because the entire country uses a single country code with variable-length NSNs. However, the 24 prefix range is shared among multiple exchanges within Oslo, and 2428 is one of several central office codes. Number portability is available in Norway, allowing subscribers to retain their 2428 numbers when switching service providers, though the geographic significance of the prefix remains tied to the original location. This means that a number with the 2428 prefix may, in some cases, be served by a provider outside the traditional PSTN, such as a VoIP service, but the number remains geographically associated with Oslo for routing and emergency services purposes.

Practical Examples

• Local dialing: 2428 1234
• International dialing: +47 2428 1234
• From a mobile phone in Norway: 2428 1234 (no additional prefix)