EFPS has nothing to do with the message about calling for clearance. Until recently a Sqawk was issued at EOBT -38 mins, thus clearance was available at this time. Now a Squawk is issued at EOBT+taxi time (25 mins atm due software problem / 20 mins normally in summer / 15 mins winter) -38 mins. Therefore a clearance is not available until a maximum of 18 mins before EOBT. If several flightplans have the same EOBT the 1st to be printed on the strip printer is printed at this time, meaning it is possible that a clearance will not be available until EOBT -15 mins.
hence asking for crew to not call for a clearance any earlier as one is not available.
I hope that that makes more sense than it reads back to me !!!
When EFPS is up and running clearances should once again be available at EOBT -38 mins. I think!!!