YSK: On iPhone, even if you have your phone on silent and Do Not Disturb, you can allow calls through from selected numbers, e.g., family, close friends, all while still blocking pesky emails and app notifications. Contacts > Click name of contact > Edit > Ringtone > Tick "Emergency Bypass."
from /r/YouShouldKnow
YSK：在iPhone上，即使你的手機處於靜音和免打擾狀態，你也可以允許來自選定號碼的電話通過，例如，家人、親密的朋友，同時仍然阻止討厭的電子郵件和應用程序通知。聯繫人 > 點擊聯繫人的名字 > 編輯 > 鈴聲 > 勾選 "緊急繞過"。