One common misconception is that a SIM card is required for your phone to connect to cell towers. However, the truth is that your phone can still establish a connection with cell towers even without a SIM card inserted.
The primary function of a SIM card is for authentication to the network. When you insert a SIM card into your device, it contains unique information that allows your phone to identify and authenticate itself on the network. This process enables you to make calls, send messages, and access mobile data services.
Even without a SIM card, your phone can still establish a connection with nearby cell towers to receive signals and communicate with the network. One way to control your phone's connections to cell towers is by enabling airplane mode. Enabling airplane mode on your device can serve as a ~privacy enhancing measure by disabling connections to cell towers.


TL;DR

Your phone device connects to cell towers even without a SIM card inserted. A SIM card is only used for authentication to the network. ๐Ÿ“ก You can disable connections to cell towers by enabling airplane mode. โœˆ๏ธ
372 sats \ 1 reply \ @k00b 2 Mar
This makes obvious sense now that you've said it but I hadn't even considered it.
reply
I'm not sure how it works in the US, but here in Europe you can call 112 (911) without a SIM card, so it's obvious that phones connect to towers. But I agree that people don't think about this.
reply
Also worth bearing-in mind it shouldn't stop at airplane mode:
  • With Airplane mode enabled but Wifi enabled, networks can still triangulate your location based upon available home/public networks it is pinging. And historical networks you have connected to.
  • Even in Airplane mode and with Wifi disabled, most operating systems will still log your location and still receive some GPS/radio signals. GPS or location services need to also be disabled to prevent this.
  • Even without a SIM card, regulations require that you any device can call emergency services. That is why this is the case.
So you need to: a) enable airplane mode, b) disable Wifi, c) disable location services and d) disable bluetooth. Only then do you have a fighting chance to shield yourself.
This video is a must watch, if this is of interest to you... https://www.youtube.com/watch?v=A9DPDE0FZeQ
Looking forward to actual hardware switches in devices to make this practice obsolete.
reply
I feel like at one point, airplane mode actually did disable all this stuff. Then later on it became a bit weaker. Perhaps my memory is wrong, but I believe airplane mode used to disconnect wifi, Bluetooth, everything. Once airplanes started offering wifi services, then you became able to enable airplane mode but then also enable WiFi so you could connect to the paid service offered by airlines.
Maybe I am misremembering, ๐Ÿคทโ€โ™‚๏ธ
reply
77 sats \ 2 replies \ @davidw 2 Mar
You could well be right.
This is why it's laughable that Apple are privacy-focused. I may still be a user of theirs, but whilst they give you many of the tools to limit their access, you literally have to be an anti-social tinhatter to truly be private on their hardware.
reply
Yea I feel like appleโ€™s privacy claims are really more relative to their competition than anything else. Doesnโ€™t make it good, just maybe slightly less bad.
sent from an iPhone
reply
100 sats \ 0 replies \ @davidw 2 Mar
๐Ÿ’ฏ they are also marketing privacy to the world, which I often underappreciate.
reply
230 sats \ 2 replies \ @kepford 2 Mar
Great post. Its one of those things many people know but we often forget about. I'd guess most people don't know this though so it is a good reminder.
Another tip. You can acquire a faraday bag/box and be even more sure your device is not communicating with anything. I recommend testing it by trying to call the phone. Trying to use other things like wifi and bluetooth. If you control a wifi network you can see if the device drops off the network for example.
Now that you have tested the faraday enclosure you can use this as an added layer of privacy/control.
reply
Any recommendations for where to get or make affordable faraday bags please?
reply
33 sats \ 0 replies \ @doofus 3 Mar
Just several layers of thick aluminum foil will condense down nicely.
reply
156 sats \ 4 replies \ @anon 2 Mar
has someone measured that airplane mode does this, ie verified? can you really depend on this in a mission critical scenario is what im asking with many phones having non removable batteries these days, this is mostly all we have left
reply
Yes, they're off. It's even pretty easy since you can just measure the waves.
What has that to do with batteries? And what do you mean "we have left"? Sounds like a paranoid mindset to be in.
reply
You can test it pretty easily. It isn't fool proof but you could attempt a 911 call or call the phone you are testing. The other sure way to block the phone's connections is to place it in a faraday enclosure. If your threat model is life or death there is no way I'd depend on a software airplane mode. I'd use a faraday bag.
reply
0 sats \ 0 replies \ @anon 2 Mar
how do you call a phone that has no sim card but is in airplane mode? ok put it in a faraday bag but im asking if anyone has tested whether just plain airplane mode is leaking any signal to the outside world we know faraday bags do work but how well do airplanes mode work on their own, is the question, and maybe this will also vary depending on the software (stock, android, ios, whatever)
yes, you can have airplane mode on and you can switch on wifi and wifi works, but is your device leaking data to towers when in airplane mode with no sim card, is the question
reply
0 sats \ 0 replies \ @joda 2 Mar
Faraday disagrees.
reply
185 sats \ 0 replies \ @hueso 2 Mar
the airplane mode preference isn't loaded until the system has decrypted (system) data, so depending on device there may be a brief period in early bootup where the modem is enabled
reply
Type writers don't. Type writers cannot usually take a sim card, and don't come with digital sim cards either.
Cigarettes also do not connect to the internet.
Therefore the most private way to communicate is by type writer while smoking.
reply
Unless airplane mode is remotely disabled...
reply
reply
Haven't done much deep state studying have ya?
reply
Ded ๐Ÿคฃ๐Ÿ˜‚
reply
Ahhaha
reply
Edward snoden did mention this.
If your phone is hacked there's no saying whats possible.
That's why he physically disconnects components. He obvi has privileged info
reply
77 sats \ 1 reply \ @davidw 2 Mar
Completely unrelated - really like those custom dividers @Skipper. Might need to steal them for future posts.
reply
Hehe :)
reply
Of course, you can do emergency calls without a SIM, did you think this use telepathy?
reply
Yes, that's why we are able to do 'Emergency calling' even without a sim card inserted.
reply
So THAT'S why Walter White and other TV criminals always break their burner phones in half when they are done with them. I always wondered why they didn't just throw away the SIM cards...
reply
I don't know if I fully trust airplane mode. Probably faraday bags would be superior.
reply
PHoNe sAyS AiRpLaNe mOdE...
#SaFe
reply