The basic premise of this idea is not a bad one. Japan already has a similar mechanism in place for earthquakes. All Japanese-made cell phones are embedded with an alarm that is triggered by the early earthquake warning system (It only sets off the alarm for the people in the area expected to be affected). However, I think the reason it works is because it has a distinct alarm noise that is built in, not able to be disabled (even in silent mode), and there is no text to read. It helps give people a few moments to prepare or get to cove because they know immediately what it means. In those cases, quick conveyance of messages is key, as pointed out. Getting a text on a tiny screen is very useless for people with impaired vision or people who are driving. Perhaps a better solution would be to have the alarm indicate that they should quickly listen to their nearest source of the emergency broadcast system (radio, television, internet). The information is still passed on more quickly than before, but with much less risk, and much less annoyance if people don't care or are unable to read the messages they receive. That being said, Congress needs to carefully think about what messages are worth triggering the alarm for, or people will simply look for ways to disable it once they get too many messages that are not important. The Japan example is easy, earthquakes are universally feared and an early warning is highly desired. A message about the change of our terror alert might not be as welcomed.