Area Code 31 – Osijek-Baranja

Overview of +385 31

The country calling code +385 is assigned to Croatia under the ITU-T E.164 international numbering plan. The national destination code (NDC) 31 is a geographic area code that routes calls to the Osijek-Baranja County in eastern Croatia. This region borders Hungary and Serbia and is a key economic and cultural hub of Slavonia.

Geographic Coverage and Major Cities

The +385 31 code covers the city of Osijek, the fourth-largest city in Croatia and the administrative seat of Osijek-Baranja County. It also serves surrounding municipalities and towns, including Đakovo, Beli Manastir, Valpovo, and Našice. The area is known for its agricultural production, food processing industry, and the University of Osijek.

Dialing Formats

When calling a fixed-line number in Osijek-Baranja from abroad, you must use the international format: +385 31 XXX XXX (or +38531XXXXXXX when dialed as a continuous string). For example, a local number in Osijek might be 031 123 456 in national format. To call this number from another country, you would dial +385 31 123 456.

Within Croatia, callers outside the Osijek-Baranja area must dial the trunk prefix 0 before the area code: 031 123 456. However, when dialing from a phone within the same area code, the trunk prefix and area code may be omitted, and you can dial just the seven-digit subscriber number: 123 456. This local dialing rule applies to fixed-line calls within the geographic charging group.

Numbering and Overlay Considerations

Croatian fixed-line numbers using the 31 area code are typically seven digits long after the area code, giving a total national significant number (NSN) length of nine digits (including the leading 0). There are no overlay codes currently assigned to this region; the 31 code remains the sole geographic code for Osijek-Baranja. However, number portability allows subscribers to retain their 31 numbers when switching operators, even if the new operator does not have a physical presence in the region.

Caller Instructions

For international callers, always replace the trunk prefix 0 with the international access code of your country, followed by Croatia's country code 385 and the area code 31. For example, to call a business in Osijek from the United States, you would dial: 011 385 31 123 456. From the United Kingdom, you would dial: 00 385 31 123 456. Mobile users in Croatia can dial the number in national format (031 123 456) when calling from anywhere in the country, as long as they are not in the same local area, in which case they may use the short format.

It is important to note that while most numbers in this region are fixed-line, some VoIP services may use the 31 code for non-geographic routing. Always verify the number with the recipient to ensure correct dialing, especially for business directories.