Cell phones (smart phones) are not a good option for private communications.
They way cell phones work is that they are actually mobile radios.
They communicate with a network of cell towers – think of these as “relays” for the cell phone network.
And for calls to be routed properly, the cell network has to know the physical location of your phone at all times – so it can route incoming calls to your phone.
That’s right – when your cell phone is not in airplane mode (or turned off) it is constantly reporting it’s location to the cellular network.
And that’s the origin of the term “cellular” network – it’s split up into cells covered with radio towers.
Additionally, your voice calls are routed through the cellular provider’s network.
Cell phone calls are encrypted – in that you can’t listen to them over the air using a generic radio – but your cell provider can of course decrypt and listen in.
How about using Internet connected applications?
Internet applications like WhatsApp are a better choice.
WhatsApp has end-to-end encryption. That means the messages you send in WhatsApp can only read by you – and the user you’ve sent them to.
But, when using an Internet connected app on your phone – the traffic is routed via your cellular provider (or on a Wifi network).
This means the messages flow through a central location – and could potentially be logged or tracked.
And generally speaking, to be Internet connected you’re going to be on LTE – and that means your physical location is known and tracked at all times.
(You can of course use a Wifi network with cellular disabled – but that is a very range limited option that is not very convenient – especially when you are on the move.)
Let’s talk about the benefits of using radios.
If you need to communicate with someone a small radio or hand-held walkie-talkie is not a bad option.
The downsides of a radio or walkie-talkie – they are relatively short range, conspicuous, and generally only good for voice communications.
Another benefit of walkie-talkies over cell phones – they can do point-to-point communications – with no “man in the middle”.
This means you can use walkie-talkies anywhere – as long as the recipient is within radio range (between 1-4 miles away).
But – those transmissions you are making are likely un-encrypted – and anyone tuned in to the frequency can listen in.
Ok, now we understand some of the limitations of smartphones and walkie-talkies.
And in some situations it would be nice to have a blend of those two devices.
Let’s talk about radio mesh networking.
Mesh networks are a special kind of radio system where you can have multiple devices talking to each other (point-to-point) but with the added benefit that each device can pass messages along to other devices to reach the message recipient.
This collection of devices that collaborate together is the “mesh” – and each device can be described as a “hop” for the message to reach it’s destination.
These are radios that will work anywhere – and these are digital radios.
That means the messages are always encrypted and you are never transmitting “in the clear” to where someone can listen in with a regular radio.
The other benefit? There is no base station involved.
That means there’s no centralized logging point or “man in the middle”.
And because this is a limited-range transmission – there is no physical location tracking for message routing.
In summary, mesh radio networks are great for short-range, private, mobile communications amongst a group of people on the move.