Just ran into this and had First Data, PCCHarge and Nashville world support on teh phone…
When setting up PCCharge for FDCN (Nashville/Envoy) here is the way to do teh merchant number…
00000
For the zeroes and MID, MID should be 6 or 7 digits. If it is 6, first zeroes you put 5 if 7 then you put 4 leading.
12/3/09 – clarification————————————
Four zeros + 7 digit MID + FOur zeros + 7 digit TID