Area Code 57 – Gorica/Koper/Postojna

Geographic Coverage and Administrative Jurisdiction

The Slovenian area code 57 is a geographic National Destination Code (NDC) assigned to the western part of the country, encompassing the historic region of Primorska and the Notranjska area. Specifically, it serves the municipalities of Nova Gorica, Koper, Postojna, and their surrounding settlements. This includes the sub-regions of the Goriška brda, Vipava Valley, and the coastal belt along the Adriatic. The code is administered by the Agency for Communication Networks and Services of the Republic of Slovenia (AKOS) under the national numbering plan, following ITU-T E.164 recommendations.

Dialing Formats and Caller Instructions

Within Slovenia, calls to numbers in the 57 area require dialing the trunk prefix 0 followed by the area code and the subscriber number. The complete national format is 0 57 XXX XXX, where the subscriber number consists of six digits. For example, a local call to a business in Nova Gorica would be dialed as 057 123 456.

For international callers, the country code for Slovenia is +386. The leading trunk prefix 0 is omitted. Therefore, the international dialing format becomes +386 57 XXX XXX. For instance, a caller from abroad would dial +386 57 123 456 to reach the same number. It is crucial to note that the area code is an integral part of the national significant number (NSN), which is eight digits in length (excluding the trunk prefix).

Overlay and Numbering Considerations

Currently, there is no overlay code for the 57 area; the geographic numbering remains exclusive to this region. However, number portability is available in Slovenia, allowing subscribers to retain their numbers when switching operators, even across different geographic areas. This means that a number with the 57 prefix may not necessarily be physically located in the region if it has been ported. Nevertheless, the tariff for calling a 57 number is based on the geographic destination, not the actual location of the line.

Services and Usage

The 57 area code is used for fixed-line PSTN and VoIP services, as well as for some mobile services that have been allocated geographic numbers. Businesses and residents in the region rely on this code for their primary voice communications. The area is known for its economic activities, including tourism, logistics (Port of Koper), and agriculture, which are reflected in the demand for reliable telecommunication services.

For callers within Slovenia, it is essential to include the trunk prefix 0 when dialing from a different area code. For example, a caller from Ljubljana (area code 01) would dial 057 123 456. Mobile phone users in Slovenia can dial the same format, as mobile networks automatically recognize the geographic destination.

In summary, the 57 area code serves a well-defined geographic region in western Slovenia, with clear dialing procedures for both domestic and international callers. Understanding these formats ensures seamless connectivity to the cities of Nova Gorica, Koper, and Postojna.