Remember that FiOS and any VOIP phones will die when power is dead for any reason.
You can use battery but if power is dead for X hours to a day then the battery will die.
Many places power does dead for wind ice etc. Many have no power for days this winter, Sandy, etc...
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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)