Slovenia received a new country code following the breakup of the Socialist Federal Republic of Yugoslavia in 1991 (which previously had +38 as country code). Additionally, the Ipko mobile phone company in Kosovo used the +386 country code.

All telephone numbers are 9 digits long (trunk prefix, 0, plus eight numbers). The first one, two, or three digits after the trunk prefix are the area code. The possible formats are: (0x) xxx xx xx, (0xx) xxx xxx, and (0xxx) xx xxx.

Originally, there was only one provider of landline telephony, Telekom Slovenije.

When making a call within the same landline area (Telekom), the area code is omitted. If a number has been transferred to another operator (e.g. T-2), it can still be reached without the area code; but to call from a transferred number, the area code must be dialed in all cases. Examples:

• 01 xxx xx xx (Telekom) to 01 xxx xx xx (Telekom) dials xxx xx xx
• 01 xxx xx xx (Telekom) to 01 xxx xx xx (T-2) dials xxx xx xx
• 01 xxx xx xx (T-2) to 01 xxx xx xx (Telekom or T-2) dials 01 xxx xx xx.

This does not apply for mobile phone numbers and VoIP numbers, where the area code must always be dialed.

The international call prefix depends on the country you are calling from; e.g., 00 for most European countries, and 011 from North America. For domestic calls (within the country), 0 must be dialed before the area code. The prefix for international calls from Slovenia is 00 (e.g., for a United States number 00 1 ... should be dialled).

An example for calling telephones in Ljubljana is as follows:

• xxx xx xx (within Ljubljana)
• 01 xxx xx xx (within Slovenia)
• +386 1 xxx xx xx (outside Slovenia)

The list of areas, grouped into historic and geographic larger regions:^[1]

¹Prior to 2000, the area codes were as follows: Ljubljana – 061, Trbovlje – 0601, Maribor – 062, Ravne na Koroškem – 0602, Celje – 063, Kranj – 064, Nova Gorica – 065, Koper – 066, Postojna – 067, Novo Mesto – 068, Krško – 0608, Murska Sobota – 069.

² Calling codes in the table are assigned to new customers by the respective provider. However, it has been possible to change the operator and retain the old calling code (along with the rest of the phone number) since 2006. Calling codes do not necessary reflect the operator, but it is not possible to transfer a mobile number to a land-based operator and vice versa.

³ Until 31 December 1997,^[2] the emergency numbers were: Police – 92, Fire brigade – 93, Ambulance – 94, Civil protection – 985.

• Telecommunications in Slovenia