Montengrin amateur radio operators may use their current callsigns until the International Telecommunication Union designates a new prefix block for the new country. ARRL will accept any prefix deemed legal by the appropriate Montenegrin authorities; please note that Montenegro is not a participating member of CEPT, so portable operations by operators from other countries (e.g. YU6/homecall) are not automatically authorized. Current Montenegrin prefixes are 4O3, 4O6, YT3, YT6, YU3, YU6, YZ3 and YZ6