This implies that with all the other warning bells and whistles there's nothing on the flight deck that alerts the crew to change frequencies?
CafeClub,
It is standard for ATC to instruct the crew when to change frequency, and what is the next agency to call. The crew would normally know approximately when the change should come, so if there is no call from ATC at about that time, they would make the suggestion to change frequency. Immediately after changing frequency, the crew would call the new ATC unit.
The system works well, but only if the crew are awake, of course.