The Call Flow Control feature is a unique feature which gives control over the routing of incoming calls with the use of feature codes. This feature is useful in a situation where an incoming number/route would need to be changed on-the-fly.
A good example of this feature in use would be when an office closes for the day. A receptionist (or user) simply dials the code (or presses the BLF button assigned to it) to enable or disable the Call Flow Control.
When the Call Flow Control is enabled (green BLF), all incoming calls will be directed to the standard IVR (or voicemail if no IVR is present).
When Call Flow Control is disabled (red BLF), all incoming calls will be directed to an IVR which alerts the caller that the office is closed.
This IVR message should explain to the user that they may press 1 to leave a message with reception or call back during regular business hours.