Originally Posted by JumpersAway79

Actually- no. You don't have to call back. It's plainly written in the scheduling section of the CRJ contract. If you have not been given an assignment by the end of your 1 hour airport standby, you are released from the airport. You are still on reserve, but you can leave (a call from that point on means I will be at the airport in 2 hours, for a departure 3 hours later).