The Bulgarian diplomatic service communicates using RFSM, a commercial derivative of the MIL-STD-188-110 standard formerly developed and sold by "IDE Group." All traffic is encrypted using its built-in "data masking" feature.
Contacts are made every day from Monday to Friday on a fixed schedule. All times listed are Eastern European Time (UTC+2 from November to March, UTC+3 from April to October). All frequencies are on the upper sideband.