Area Code 21 – Tehran province

Overview of Iran's +98 21 Geographic Area Code

The +98 21 country calling code and area code combination is assigned to the Tehran province, encompassing the capital city of Tehran and its surrounding metropolitan region. This geographic area code is part of Iran's national numbering plan under the ITU-T E.164 standard, serving as the National Destination Code (NDC) for fixed-line PSTN and VoIP services within the province. The code is exclusively used for landline numbers, distinguishing them from mobile and non-geographic services.

Geographic Coverage and Administrative Jurisdiction

The 21 area code covers the entire Tehran province, including the city of Tehran (the national capital) and its adjacent counties such as Rey, Shemiranat, and parts of Karaj's eastern suburbs. As the political, economic, and cultural hub of Iran, Tehran's numbering capacity is substantial, with a mix of residential, commercial, and government lines. The province is divided into multiple telephone exchanges, each assigned a range of subscriber numbers within the 8-digit local format.

Dialing Formats and Caller Instructions

For local callers within the Tehran province, the area code is often omitted when dialing a local number, using only the 8-digit subscriber number. However, for calls from other provinces within Iran, callers must dial the trunk prefix '0' followed by the area code '21' and then the subscriber number: 0 21 XXXX XXXX. For international callers, the format is +98 21 XXXX XXXX (or 0098 21 XXXX XXXX from many countries). It is crucial to drop the leading '0' when dialing from abroad.

Number Structure and Overlay Considerations

Tehran's subscriber numbers are 8 digits long, resulting in a total number length of 12 digits when including the country code and area code (excluding trunk prefix). The area code 21 is not overlaid with other geographic codes; it remains the sole fixed-line code for the province. However, due to high demand, some numbers may be allocated to VoIP providers, but they remain geographically tied to Tehran for regulatory purposes.

Practical Examples

To illustrate, a typical Tehran landline number might be +98 21 5566 7788. A local caller would dial 5566 7788, while a caller from another Iranian city would dial 021 5566 7788. An international caller would dial +98 21 5566 7788. Understanding this format ensures accurate connectivity for both domestic and international communication.