The pilot requested, from Sydney Flight Service International, the NOTAM status of R674. The Flight Service Officer (FSO) checked the status using the FISOR system and advised that the area was not active. R674 is a military restricted area and is active on a 24 hour basis, any change to this status is advised by NOTAM. When the FSO checked the system he received a message which indicated that there were no current NOTAMs for R674. The correct intrepretation of this message is that the area would still be active. Apparently the FSO, who was not familiar with the normal status of the restricted area, assumed that if no NOTAMs were current for the area then it was not active. He should have advised the pilot that there were no current NOTAMs for R674. Significant factors 1. The Flight Service Officer made an incorrect interpretation of the message on the FISOR system.