Bulgaria 3TO service card 1988. PKM-392/88
The national phonecard payphone roll-out for Bulgaria, began in 1988, using the magnetic cards produced by ZIMEX in Eastern Germany.
After the small scale trial in 1987 with 3 digit serial cards (PKM-261/87 meaning 1987 dated on reverse), the same 4 card values were used in this public issue of 1988.(PKM-392/88) A number of serial number varieties are known, with slightly different fonts. Additionally there are a number of denomination overprints in Leva, and also $USD.
These will be added in at a later stage