At bmi, on the A320 family, once the cabin crew have reported to the flight supervisor that their respective cabin areas are secure via the interphone, the FS
will push the cabin ready button on the FAP (Forward attendant panel) which lets the flight crew know that we're all ready to go. If the cabin becomes unsecure (passenger standing up, medical situation etc) the button is deactivated. As we approach the holding point, the pre take off checklist requires that the cabin status is checked, and the seatbelt signs are cylced off / on which sounds a double chime in the cabin indicating to the cabin crew that we're off. Prior to landing, we get a "cabin crew 10 minutes to landing" PA from the flight crew, at which time we secure the cabin, sit down, call in our checks to the FS
who presses the cabin ready button. As the landing gear comes down, the aircraft automatically illuminates the exit signs and sounds a single chime, and the seat belt signs are cylced by the flight crew sounding a double chime (so we end up with three chimes).