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: 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."