For a very long time, the state-owned Bulgarian Telecommunications Company (BTC) had a monopoly on fixed telephone networks. However, it ended when a special law was adopted. BTC was privatized in 2004 and competing operators appeared.

Larger areas, such as Sofia, Plovdiv, Varna, and Burgas, are subdivided into zones. Although one cannot further reduce the number of dialed digits, the number itself shows which zone it is located in. For example, in Sofia, numbers starting with 2, 82, 92 are located in the Western suburbs, 7, 87, 97 in the Eastern suburbs, and 98 in the central area.

In the recent decade there is an intensive process of replacing the old analog switches with modern digital ones. In areas where both analog and digital switchers are operating, a subscriber number shows by its first digit if it is connected to an analog or a digital switch. In some areas it is even possible to guess if a subscriber number was changed from analog to digital during its existence or was subscribed as digital initially. For example, in Blagoevgrad a number starting with 88 was subscribed as digital, and a number starting with a single 8 was analog before.

The first digit also shows if a particular subscriber number is operated by BTC or another operator.

The area codes are always cited with the trunk code. However, within the area, or when the Sofia code of (0)2 can be guessed from the context, it is omitted.

GSM networks six-digit subscriber numbers Until 20 July 2003. In accordance with the limit of eight digits for the domestic part of a number. With the increase of subscribers (and an international requirement), all (except Vivacom, which started operations in 2006) acquired new access codes. On 20 July 2003, Mobiltel three codes ((0)87, (0)88, (0)89) and Globul two ((0)98 and (0)99). When these limits were also to be overwhelmed, seven-digit subscriber numbers and single access codes per operator were introduced. Mobikom had gone through a similar change in mid-90s (from (0)799 to (0)48).

This change provokes an error in citing mobile numbers, quite similar to that of erroneous UK telephone codes. The first digit of the subscriber number is most often cited as part of the access code, e.g. (0)887 XXXXXX, instead of the correct (0)88 7XXXXXX. This error remains for new subscriber numbers and even for Vivacom numbers which have never been six digits long. However, unlike the situation in UK, this error has no effect since a mobile number must always be dialled with the access code.