FIOS , Cable Vision and Time Warner plus many other carriers throughout the country have an optical interface modem that connects their outside lines to your telephone service (a modem for short) at your building.   It uses your house power from an electrical outlet to power it.   When the house power goes out the system/modem then operates from a  battery of some sort when there is one and that is the issue.   They (the providers of such) are all saying they do not want to provide or service a backup power source and when in some cases want to use flashlight batteries that you have to get, install and change when needed.   So what this really means is that when the alarm communication attempts to use the telephone/communication/internet lines when there is a power failure there is a good they will not be available to work.   This can affect every alarm dealer in some way and they may not know it there is a backup battery and even if it works thus a failure to communicate. 
    THERE IS A NEW GREAT CONCERN THAT COMMUNICATION SERVICE PROVIDERS ARE NO LONGER ARE PROVIDING RELIABLE OR ANY FORM OF POWER BACK UP FOR THEIR EQUIPMENT IN THE EVENT OF A POWER FAILURE TO INSURE COMMUNICATION THAT DOES AFFECT THIS INDUSTRY PLUS”   A new possible of a failure to communicate to the central station when called upon.  (just like in the movies Cool Hand Luke with Paul Newman “What we have here is a failure to communicate”)
    Recently I can across some interesting facts that were stated to me from an employ of this communications firm that said that his company is going to power the backup power unit instead of with rechargeable batteries but with non-recharge able D size cells so that the user maintains it easily by going out and buying their own batteries.   The dry cell batteries are not supervised or give an indication if they need to be changed and if so do not meet NFPA 72 requirements plus others.   Super Storm Sandy caused an enormous amount back up of calls to do so and they want to get away from that.   The intent here is supposed to make things easier but the real intent is not for them to have to service the unit.   A new concern.   
    So what are the issues here?   Is the customer really going to do this, are the batteries going to be good when called upon and if so for how long of a time period?   Also as noted in the instructions it that you have to turn this back up on when the power interruption happens and it should remain off all other times, who is going to do that?   It should also be noted that everything discussed here is not limited to just residential applications. 
    This will be another problem for the industry especially when you do not know what kind if even there is a backup supply and may assume there is a backup supply.    Statements on the internet say they even if you want a battery backup now they will charge extra for it and it is no longer included in the installation for free (see the link below).  
    The big question for the industry NOW  is does your job that uses these any of these service providers provide backup power at all and if so what kind of.   The assumption that it is there and being maintained no longer exists and it would be a hard lesion to learn after the is a loss at the premise.
    Here is a link discussing that none of them intend to supply back up supplies if they can avoid to do so:

Verizon to eliminate free backup batteries for new residential phone customers

Decision by telecom giant could prevent 911 access during blackouts.  See this link for article:

     For a recent letter from Verizon to the FCC explaining difference between communication over fiber and the FIOS service, see this link:  http://apps.fcc.gov/ecfs/document/view?id=60001048919
     For pictures of installing battery back up see this link:  https://www.verizon.com/supportresources/docs/Power-Research-Instructions.pdf