Exact Answer: 5-6 minutes
Cellphone networks are likely to go down in mere hurricanes. They would not be functional in any meaningful amount of time in an apocalyptic scenario. Cell networks rely on two things for their function: A) electric power, B) a backhaul to a wider network.
Both of these things are likely to go down when civilizations eat themselves. When the electric power goes out, cell networks only have a limited fuel supply in emergency backup generators, and when those tanks run dry, that’s it. And that’s assuming they have a backup generator at all. On the contrary, it will decrease network connectivity.
How Long Would Cell Phones Work In An Apocalypse (And Why)?
| Reason | Time Duration |
| Because cell phone networks are known to be cut out just after a grid loss in a severe storm. | 5 minutes |
| If you can get to a working data center with good backup power, then you might be able to use the internet at least. | 6 days |
The rest of the internet could remain up and running, but if the backbone provider in the area that services the trunking system that the local cell sites use goes down, cellular service in that area will be nil. It will probably not be possible for one handset to call another handset when both are standing right at the electrically operable cell tower since the cell site can’t communicate back to its operator’s servers for billing and accounting database activity.
Without power, cell phones would fail since the towers themselves need the ability to process. 3G/4G is still run off the buildings, just a different frequency. Perhaps one could have a single tower in a small area operating, if it was connected to some sort of power source and have a very limited reception (within a few miles) anyone in that area could communicate, but that would only last if they had some way to charge their phones.
One relies mostly on how the cell networks connect, the backup power situations (battery, diesel/gas generator, natural gas generator), and the region of the tower. And many cell sites would stay up but you would see a general failing of wired infrastructure as the switches go offline.
Also, high-speed/broadband internet would pretty much be relatively quick (within a day or two most likely) without a reliable power supply controlling the master servers each country has.
Why Would Cell Phones Work So Long In An Apocalypse?
If there are two or more sites, each with enough power to run a computer, you could take help of old dial-up modems and create a network for communications; however, one would probably need to write/find some program as an interface so the perspective parties could use it that way. Probably easier to use AM/FM or HAM radios for the same objective.
Satellite to Satellite transmissions would stay up the longest, but the ground stations would begin to fall for the same reason as the cell phone and landline networks. As mentioned, cellphone towers work from the power grid, and to call someone, it takes two operating towers (assuming there is some range between the phones) and an infrastructure (network) in between; all require power.
That infrastructure might be on various power networks, and if one fails, you can’t connect. Power plants induce power (electricity) itself, and those need to be actively restocked and conserved to stay operational.
The networks themselves need to be regulated too. All that is a lot of chances to fail somewhere, taking your phone call with it. It would take a day or two before you can’t take your calls anymore. If there’s going to be an end of civilization, you should opt for the good old longwave radio as a means of communication.
Conclusion
GSM- Global system for mobile communication is a system where all your GSM device needs to do is receive the signals and triangulate your stance to work as long as the satellites do. However, that’s not true.
Due to several reasons, satellites drift a bit, and that drift has to be actively compensated simultaneously. If that stops then, GPS will become indefinite very fast to the point it’s useless.
Commercial satellites themselves will function for a long while. Still, unless you also got the access technology up and running, that won’t do much good, unless maybe you use a satellite phone to call another satellite phone.