How Phones Work During Power Outages

by | Aug 5, 2008 08:00 PM ET

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Marshall Brain

Hi, I'm Marshall Brain with today's question - Why does the phone still work when the electricity goes out? If you have a wired phone that plugs into a phone jack in the wall, you've probably discovered that your phone works even in a power failure. One of the relative miracles of modern times is the reliability of the landline phone system. The power goes out fairly often for most people. Sometimes it's only out for a second, but other times it can be out for minutes, hours, or even days.

Your landline telephone, on the other hand, is always working. Why is that? Between your house and the phone company's office, there's a dedicated pair of copper wires for your phone. Those wires are almost always buried, so ice storms and hurricanes won't cut them. The phone company supplies the power that your phone needs using that dedicated copper pair. The phone company uses batteries or generators to keep the power going even if there is a power failure, so your phone is basically going to work all the time.

Many cell phones offer this feature, as well. Your cell phone runs off batteries, and the cell phone tower has generators that they use in power failures, so your cell phone will probably work all the time, as well. But if you use a cordless phone in your house, it will stop working in a power failure. That's because the base station plugs into the wall for its power. If you want to keep that phone working, you need to connect the base station to an uninterruptable power supply. Do you have any ideas or suggestions for this podcast? If so, please send me an email at Podcast@HowStuffWorks.com.

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