Get through even when a phone is on silent.
Emergency Ringer will reside on the phone of the purchaser, allowing that person to select contacts who will be able to make the phone break silence when necessary. Have a challenge/response so not every call the select contact makes the willl make the phone break silence. After all the phone may be on silent for a reason and not every call is important. Be lightweight and not use many resources or battery. Help find lost android phones on silent, or apple phones without needing to log into icloud.
