ˈwake-up ˌcall BrE AmE noun [countable]
1 . an experience or event that shocks you and makes you realize that you must do something to change a situation:
The success of extremist groups in the elections should be a wake-up call to all decent citizens.
2 . a telephone call that someone makes to you, especially at a hotel, to wake you up in the morning SYN alarm call