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Make calls without cell service or wifi
Hello,
I was with my friends in remote mountain areas travelling and there was no cell coverage for some time in many locations. We had to stop cars to communicate in this situation and I wondered if there are any apps that can make calls to nearby android devices?
Like using one's Wi-Fi hotspot (without internet access), more like local area network call. Anyone know anything similar if that exists?
Comments
Satellite phones may be could work?
don't rely on phones, use HT. you can easily cover 1-5km range with that, ~10km with more serious stuff.
Check out setting up a mumble server https://www.mumble.info/downloads/ and using their 3rd party android app. Should work without internet.
Only if you have other people to relay your data in a nearby vicinity, but on top of all, going to extremely remote areas without a sat phone is not only stupid (if you go by yourself) but irresponsible if you take others with you. Luckily I'm not your friend.
Garmin's satellite communicators work pretty okay. Can be a pain in the ass sometimes when you're stuck in a heavily wooded area, but if you can get above the treeline or someplace with a clear view of the sky the messages get out pretty fast. https://www.garmin.com/en-US/c/outdoor-recreation/satellite-communicators/ . When I was backpacking it'd have trouble in thick forested areas but on mountain tops or when getting into the alpine zone above the tree line it was pretty quick.
Not cheap, but sat devices are pretty rad.
Hand held radios also work, pending local licensing requirements. Even then, a handheld 5W radio is going to be limited in range and often only really work (well) if you have some form of line of sight to the other person. (Ex: You on top of a mountain, them down below. Or both a couple miles apart in an otherwise not too hilly or not too tree covered terrain.) That changes and is less of a concern if you're going through a nearby repeater and are both tuned to the same frequency and using the same tones to access it.
EDIT: Neither really do 'calls' but I guess it depends on what you're trying to do. If you just want to make sure your buddy is still alive or send your coordinates to him and text, "Found a good campsite, come meet" or something, the Garmin works great.
Mate 50 has satellite SMS.
@Francisco
Reminds me of the story of buyvm helping customers build services during natural disasters many years ago, do you still remember it?
USRP B210 + OpenAirInterface5G + free5GC makes you a cellular base station.
Any cell phone within range of the base station can call each other.
Carry one in your backpack or vehicle, and you get full signal bars at all times.
Apple should extend the Satellite emergency SOS service to regular communication too.
Any idea how much this band costs? Basically like asking "free worldwide phonecalls" because all emergency numbers are free, in any country.
Really dumb idea but I wonder if one person setting up a mobile hotspot exposes a local IP address (e.g. 192.168.x.x) that others can use to connect to the hotspot to a voice server app on that hotspot phone.
That said, whether a mobile hotspot can span the range of a couple of cars (assuming very close following distances), I am less sure about.
Never tried this but definitely worth looking into.
Or as someone else suggested, try walkie talkies?
I'm interested in what the OP ends up using either way, since visiting extremely remote areas of the Earth away from modern civilization is on my bucket list.
...
I second this, the inReach stuff is great. I've used it in remote Australia (which doesn't have the treeline problem, only crocodiles and lack of water trying to kill you
)
Most of the offline solutions for Android (like Briar or Bridgefy apps) support text only but if you need voice (in the form of push-to-talk probably) you can try any of these (they work offline over Bluetooth/Hotspot/Wi-Fi direct):
https://play.google.com/store/apps/details?id=it.masmil.walkietooth
https://play.google.com/store/apps/details?id=com.androidintercom
https://play.google.com/store/apps/details?id=com.remaller.android.wifitalkie_lite
For me only the first app is installable through Google Play. If you're getting "This app isn't available for your device because it was made for an older version of Android" message for the other 2 apps you can try to extract the APK and run it anyway, it might work or not (I haven't installed any)...
There may be other similar apps.
if you want to go the hard way here's a tutorial for using an Android device as a Mumble (murmur) VOIP server [No Root]:
https://forum.xda-developers.com/t/guide-using-an-android-device-as-a-mumble-murmur-voip-server-no-root-required.3473061/
it also makes you pay the government for a license or you can get fined (?)
When Congress disagrees with president, the federal budget doesn't get approved, and the federal government will shutdown.
When the federal government is shutdown, so is FCC, the only agency that can enforce frequency band licenses.
You can transmit at any frequency band using maximum power.
Unless a plane crashes down, you won't be fined.
sounds good
Someone I know set up a cheap UHF transponder connected to his telephone landline. With a paired radio in the van, he could make free phone calls within 50 km from home.
This thread feels too much like reinventing the wheel.
https://en.wikipedia.org/wiki/Walkie-talkie
Walkie talkes is what you need.
While using wifi or whatever to basically turn mobile phones inte walkie talkies sounds like a cool idea, you will at best be able to communicate within the reach of the phones wifi. In reality, this is about as far as you can throw it. If you are in different cars, your lucky if you get half that.
You can buy cheap as walkie talkies with 10x that range for a few bucks. If you are travelling in remote areas frequently enough that this actually is a problem for you, spend a few extra bucks and get some decent radios with car chargers.
Something like https://gotenna.com/ might be useful in this particular case.
It looks more like a hi-tech devices used by military operations and intelligent departments.
I think that’s their most common use case these days but they still have a “personal use” page on their site https://gotennamesh.com/ though it looks like there’s a waitlist right now.
I used to think it was an either/or type of thing, but on second thought, drinking the water in which crocodiles swim is asking for trouble.