The system will automatically send telephone notifications to all listed and unlisted telephone numbers in an area affected by an emergency (Including TTY/TDD.) If a number is busy when dialed, the system will redial the number. If the call is answered by and answering machine then the message will be left on the machine.
Residents of the city of San Diego need to know that they must register their cellular phone numbers in order to receive such calls, as these numbers are not part of the system. Registering your number is easy and can be accomplished in a matter of moments online via the city Office of Homeland Security Website.