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Millions of smart meters will brick it when 2G and 3G turns off
(www.theregister.com)
This is a most excellent place for technology news and articles.
It's difficult to eliminate the use of electricity, although generally you'd have them on a battery backup.
Internet is required to contact the fire department or other emergency center (these panels tend to do more than just fire). Used to be just phone lines using a touch tone code, but phone lines are going away. They're pushing hard for cloud solutions now for security panels - I imagine fire will go that way soon enough.