As the Twitterverse buzzed about tornado warnings Tuesday night, many of the tweets expressed confusion about text messages they received alerting them to tornado warnings issued.
Wrote Twitter user @SheedaBeeda: "
The system, through which federal emergency management officials can broadcast weather, AMBER or national emergency alerts, has been in place since May. Wireless industry association CTIA
, including whether you can opt out of them, whether they cost you money, and whether alerts can find you if you are out of your normal service area.
For the record, you can opt out of all but the national emergency alerts, they are free, and alerts are based on your current location, not your home location.
Wondering why your friend or family member received an alert and you didn't? Not all phones are compatible yet -- iPhones aren't, for example. Here are lists of compatible devices by carrier:
. Links to other service providers can be found at the CTIA link above.
Many people asked why they received messages when they weren't in the area of the tornado warnings. The system broadcasts the messages from area cell towers, so it doesn't precisely focus on the area of warning. That also means the system isn't tracking your location, and it doesn't know where you live -- it simply sends out the messages to cell towers near the weather danger.