Bulgaria has three main operators: Vivacom (BTC), A1 Bulgaria, and Yettel Bulgaria (formerly Telenor). All three have launched 5G in Sofia and are expanding to other major cities. 4G LTE covers Sofia, Plovdiv, Varna, Burgas, Stara Zagora, and main towns throughout the country.
Sofia has excellent 5G and 4G coverage across the entire city, including the historic center, Vitosha Boulevard, the National Palace of Culture area, and Sofia Airport. Plovdiv's old town on the three hills has strong 4G throughout. Varna on the Black Sea coast has solid coverage across the city and resort areas.
The Black Sea coast from Sunny Beach south to Sozopol has good 4G in summer. The Rila Monastery area in the Rila Mountains has 3G to 4G at the monastery complex. Higher mountain trails in Rila, Pirin, and the Rhodopes drop to 3G or have no signal on ridgeline routes. Download offline maps for any mountain hiking above 2,000 meters. The Valley of the Thracian Kings near Kazanlak has 4G in town and at main tomb sites.