With the proliferation of cordless phones, the requirement for electrical power to make phone calls is more and more of an issue to consider during an emergency. Cell phones are a good backup, but calling 911 on a cell doesn't let the police know where you are.
My phone is Internet based, and my internet connection is on battery backup (both the connection itself as well as the routers needed to connect everything). I have a corded phone in the house so that calls can be made even if the electricity goes out, but even then it's a limited time frame since the batteries can only run for a brief period.
There was a horrific story recently about a woman who was killed with a machete and her daughter left for dead where the thugs cut the electricity to the house before entering. I know that the phone in my bedroom requires electricity to work, so my wife would not be able to dial 911 in a similar situation. Granted, she can dial up 00 Buckshot from a 12 gauge as a substitute.
Just something to think about.