Does anyone even have a landline anymore?
Most everyone I know uses cell phones for everything. After three years, I barely went back to a "real" landline.
In the event of an emergency, city/government officials activate the Reverse 911 system which, in theory, would call all the residents within a disaster zone on their landlines if they needed to be evacuated. In reality, most small sized cities/towns don't have the resources for their own Reverse 911 system, and outsource it to other cities, which means when the Reverse 911 call comes, it's not a local number.
A friend of mine recently answered an out of state number to find out a SWAT team was down the street and he needed to stay in his house. After calling 911 to verify the call was legit, he was glad he'd answered.
Do you answer your phone if it's an unfamiliar out-of-state number?
If you have a VOIP or cell phone, you can register it HERE, www.vecc9-1-1.com, to be certain you'll be notified if the Reverse 911 call is activated for your area.