Fortunately, I have had to call the emergency service only when my kids or my husband were seriously ill or someone from our family was traumatized ( herted ) and I couldn't help them myself. Usually they arrive within 10 - 15 minutes. The emergency medical services provide medical care out of hospital. If they come very quickly it can help to avoid the complications or even safe your life. Pull over if you see an ambulance coming. It can safe the valuable minutes for somebody. I hope I'll never have any reason to call the emergency services .