[Ray_from_Mi]

The safe mechanic is to simply blow your whistle (one extended blast) and extend your arm pointing to the bench calling the time-out. Once the coach notifies you if its a full or 'short', then signal that to your other officials and the other coach. If there is no indication from the coach (and I let them know this when we meet prior to the beginning of the game) then he/she will receive a full time-out.