I always found it super cool that when there’s a loss of power, even during the big blackouts, you could still use landlines. Are cellphone towers also separately powered, or is there any push to make them so like landlines. The fact that you can use a house phone during a power outtage seems like the only reason left to bother with them anymore.
Cell towers have battery backups that will last for several hours. If a blackout extends beyond that then they stop working.
Yeah, they have battery backups at the towers (next time you see a tower, look for a small building in the fenced in area…that’s where we keep the batteries at least), for the microwave uplinks and at the telco network centers. As Whack-a-Mole says, if power isn’t restored within a few hours you’ll eventually have something fail and no more cell phone in the effected area. I don’t know how long the batteries last on cell towers, but our microwave system has 8 hour battery backup for infrastructure, and our data center has 10 hours (with the use of a building generator).
-XT
I’ve had a week long blackout, most of my county lost power for at least 2 days, many longer. Cell service for me worked, not just voice but internet also. I’ve heard that different cell carriers have different reputations when it comes to service during blackouts, and many with competing services lost cell service.
About a year ago, we lost power due to icestorms for around 13 days. Cell service of several carriers was off/on the whole time with it being rather non-dependable (more off than on) overall, imo. That sure was a looooong cold two weeks… cell service went bad within a few hours (at most) of electric grid failing and a crap-shoot for the duration.
One factor to consider is that a cell tower may not be on the same commercial or residential grid as the folks having the blackout. It would depend on if there are alternatives, and what the costs are. Also, diesel generators are probably used at some of the more critical sites. On our microwave network the nodal sites have diesel generators, while the edge sites just have battery backups of one kind or another.
(I’m not nor have I ever been a cell engineer, so you can take the above with a healthy grain of salt…I just know how systems I’ve worked on and designed function)
-XT
Good to know there is some backup for cell service. I guess the salient question then is, how much reserve is there for the landlines?
Also blackouts usually do not take out an area big enough for a cell phone to reach an a site. You may not have 3g and 2 bars but it will still work, unless you are talking county level black out
The power to the cellphone towers might not be the determining factor in an emergency.
My geographical area was once served by a single fiber cable connecting 27,000 people to the rest of the world. This cable served all cellphone towers and landline phone COs.
A farmer lowered his backhoe into a ditch and unintentionally severed the single fiber line once (twice, actually, but a different time and different farmer). As soon as the local CO (=Telephone Central Office, like a hub) lost the connection, all long distance calls were cut off.
As soon as all the cellphone towers lost their long distance connection, they automatically went dark, pulled the plug, shut down, rendered useless, because they couldn’t make any connection, even to local numbers which normally went thru long distance lines back to local. They had power, but no signal, so they turned themselves off.
This happened to me some years ago, but I had no idea what was going on, when I had to make some critical calls from Wisconsin to Los Angeles. I thought my cellphone would be the saving grace, but it was dead, too. I finally climbed on top of my house and was able to connect to a cellphone tower on the other side of the break with weak signal, and at least let my clients know that there was a problem with communcation.
So there are a number of factors during blackouts, not just power availability.
When the great New York City blackout happened (yes, the whole Northeast was affected, but who cares?), the cell phones didn’t work either. And, there were a few places without regular landline service too.
Land lines will be served with emergency generators that will start with in seconds of the phone company looses power.
Effectively, almost infinite.
Every CO has battery backup that can power them for hours to a couple of days.
Then they have emergency generators that can power the office (& recharge the batteries), which normally come on automatically when power is lost.
And they have a supply of fuel for these generators. Major CO’s will have a diesel tank that contains hundreds of gallons of fuel, enough to last for many days. Plus the staff there will quickly arrange for delivery of additional fuel as needed. They will get priority on delivery of fuel,too – telephone communications is considered a vital service during emergencies.
I’d hazard that even if the CO has a generator, not all the equipment that connects your phone to the CO does. It is increasingly common in NZ for residential customers to have their lines fed through a roadside cabinet. That allows closer connection for your DSL line to the SAM (Services Access Manager) than running copper back to the CO. Run fibre to cabinets and only have short copper lines to the customer.
The roadside cabinet typically has 4-8 hours battery capacity, and that’s if the batteries are regularly maintained and replaced. It can happen that the battery is shot, so you get 20 minutes before the cabinet fails in a power outage.
Commercial customers also have nodes supplying their phone services and some may be housed in the customer’s building. They will have batteries too, but the customer’s equipment may not so their landlines fail immediately.
I’m a support engineer for transmission systems, both roadside cabinets and trunk systems, for a telco, and have a reasonable amount of experience in this field.
Well, not all landlines are independent of the AC current, anymore. I have Vonage for my home phone. It is dependent on its own modem, which is powered by the wall outlet. So, no power, no home phone.
In the case of a really extended outage, cell companies may well be able to roll out the COWs (Cell on Wheels). They’re more commonly used to bolster coverage for big events, but they would be usable in emergencies.
Now, if you’re talking an entire city being out, there’s not going to be nearly enough, so depending on the nature of the disaster they would be set up around shelters or something, but they would be available.
This isn’t typical, but we had a power outage Saturday (the 8th) that lasted a little over 10 hours. Our land line still worked, but cel phones (AT&T) were out until yesterday (Tuesday) morning, even though all power was restored a little after 6PM Saturday evening.
I’m guessing that there were a number of cell sites that did not have a generator backup. When the battery voltage reaches a certain threshold the equipment will begin to shut down (this is to protect the equipment). Once power is restored and the batteries begin to recharge that equipment must be powered up and tested before it can be put into service. The batteries must be tested to make sure they are still viable. Once that testing is complete the site can be put back on the air.
As you saw that can take some time. There are only so many techs covering a geographic area and despite the amount of overtime that can be earned those techs need to sleep eventually.
But there is backup power available for that, too. I have phone service thru Charter (cable TV), powered like yours thru a modem, but the modem has a 4 hour battery inside and I rotate that with a spare. It works.
It was very breezy that night, too. In fact, the wind was whooshing overhead.
I was in that blackout. It wasn’t because the towers didn’t have power. It was because they were jammed with everyone trying to use their cell phones. Congestion limits the use of cell phones.