wake-up call

/W EY1 K AH0 P K AO0 L/
noun
  1. 1

    A telephone call to awaken someone at a certain time, especially one requested by the person while staying at a hotel.

    โ€œShe requested a five a.m. wake-up call from the front desk.โ€

  2. 2

    An alert, reminder, or call to action caused by a dramatic event.

    โ€œThe recent deaths should serve as a wake-up call to others at risk.โ€

Source: https://en.wiktionary.org/wiki/wake-up%20call