BULASTA has and maintains one of the best developed communications infrastructures in Europe in the field of air traffic communications. It offers a wide variety of services and applications:
Air Navigation Telecommunications Information Network (ANTIN) is designed to assure the constant transfer of air traffic information among the various infrastructure units and the centers for air traffic service in the country. It consists of two sub-networks based on Asynchronous Transfer Mode (ATM) swithes and TDM (Time Devision Multiplexing) technologies. A third IP (Internet Protocol) sub-network is planned. ANTIN interconnects 12 units. The interconnection between the sub-networks aims at the optimal use of communication line resources and guarantees uninterrupted functionality of the aeronautical equipment. Meanwhile each node is connected by at least three independent channels to the other network nodes to ensure the necessary levels of safety and reliability. This involves the use of digital radio-relay systems (DRRS), channels of the telecommunications operators or of the Ministry of Defense.
The international connectivity for voice and data exchange is provided by leased digital and analogue lines. A network based on IP routers has been set up aiming at more efficient use of the leased lines capacity and automatic re-routing of the traffic in case of a failure. Currently the network covers Air Traffic Management Centers in Sofia, Varna, Bucharest, Constanca, Skopje, Athens, Simferopol, and it will soon cover Istanbul and Ankara.
BULASTA uses four operational Voice Communication Switching Systems (VCSS) supporting all standard MFC-R2, CB, ATS-QSIG and ISDN interfaces. The systems were installed in Soifa, Varna, Bourgas and Plovdiv ATCCs. They provide the functionalities necessary for voice connectivity of flight managers and aircraft crews as well as flight managers from neighboring countries VHF air-ground radio communication is provided by 13 receiving-transmitting centres with over 300 radio stations servicing more than 30 radio channels. In line with European Commission Regulation №1265/2007 radio channel frequencies LW 8.33kHz were introduced in 2008 in some of the regional centers for ATS in Sofia.
The Single Air Traffic Control Center introduced an ICAO - AFS international telecommunication network AFTIN/CIDIN. The center will be converted to AMHS system to comply with some ICAO requirements according to which Europe should convert from AFTIN/CIDIN to ICAO by 2010. The new system guarantees the exchange of air navigation messages and is in direct relation with flight safety and air navigation services. The main computer is located in Sofia with remote stations in Varna and Bourgas.
A VSAT station is located in Varna providing the operational back-up voice communication with the countries of the Black Sea region - Bulgaria, Ukraine, Turkey and Romania.
The whole communication equipment and all company networks are covered by real time surveillance and control systems - a mandatory element for timely malfunction diagnostics and troubleshooting of equipment failure.