Went to the site today - customer said it hasn't happened since Friday. Made many tests calls, could not reproduce the trouble. Being new to Iwatsu I now know there's an automatic system reset feature, This one is set for 4a.m. daily. Maybe that cleared the trouble? But last week the trouble occurred for a few days until I reset the 408 card. I wonder if like Rolm systems - the system will not reset if there's at least one active connection. I'll try it in the shop PBX.