According to the EC Regulation, 8.33kHz spacing between voice channels is implemented in Slovenian airspace.
The changes are published in the AIP, here is a brief summary.
LKZP Cerklje 118,555 23.3.2021
LKZP Maribor 119.205 23.3.2021
LKZP Brnik 118,005 24.3.2021
LKZP Portorož 124,880 24.3.2021
LOWER 135,280 25.3.2021
FIC 118,480 25.3.2021
Aircraft not equipped with appropriate radio stations are not allowed to enter controlled airspace. In case of emergency (technical problems, weather situation), the appropriate air traffic control unit must be contacted on 121.5MHz.