I decided to purchase a one-way pager, a programmer, and a paging subscription to satisfy my curiosity about pagers.
In this post, I am explaining my thought process and describing some of what I have learned about how pagers work. This is especially relevant to the national paging network in the Netherlands, but hopefully others also find it interesting.
The cellular network
Cellphones give us the ability to reach others and to remain reachable regardless of our location if within a network’s coverage. The network infrastructure is continuously evolving in ways that make it more efficient, secure, and reliable.
One way that the network becomes more efficient is by improving its device tracking abilities to reduce the amount of radio broadcasting resources needed to deliver data to the recipient. Security and reliability are improved by having two-way communication between the network and devices such that devices can be authenticated, data correctly encrypted, and message delivery confirmed.
A participant within this network must accept one or more of their device’s unique identifiers (at the very least the IMSI, often also the IMEI) is associated with an approximate location.
Since I do not want to accept these terms, I do not carry a phone with a SIM card on me.
A burner phone and an emergency pre-paid SIM card gives me the opportunity to connect to the network in the case that I need to contact someone immediately.
However, this does not give the opportunity to others to reach me in the case that they need me or worry about me. This is not common, but there have been cases in which being reachable would have been good.
LoRa / Meshtastic
Last year I learned about LoRa radios and the Meshtastic network implementation. These devices allow one to send encrypted messages directly between devices. The range is decent, especially if there is a line-of-sight between devices. With Meshtastic it is possible to create a network of nodes that route messages, and to make use of tunnels over the internet to connect nodes that are very far apart.
So far, my favorite use-cases for Meshtastic are communicating with my partner as I approach an area to meet them, communication during festivals/events, and when travelling in a small town or camping.
It is a great tool in some contexts, but I cannot be reliably reached with it.
The Pager
I am currently living in the Netherlands and so what I say is most relevant to the Dutch paging network ‘KPN Nationaal 3’. Messages are broadcast using POCSAG 1200 at 172.450 MHz. I know that the situation with paging networks vary across the world, with paging networks being no longer available in many countries, but I don’t know the details. It may be that the system here is rather special and unique.
The paging network is considered a legacy broadcasting system. Messages to the network are broadcast by transmitters distributed across the full coverage range. The message that is broadcast contains the RIC (Receiver Identify Code) and the message in plain text.
Anyone with an SDR (Software Defined Radio) device can decode and log all of the unencrypted messages. Here is an example using SDRConnect + multimon-ng:
Using a programming interface, a user can select the RIC codes that they want their network-tuned pager to be responsive to. The pager will beep and display on the screen messages sent to that RIC. In my case, the seller of the pager assigned a new RIC from their pool to me and programmed the pager to listen to it.
A pager does not have a built-in transmitter, and so it does not reveal any information to the network.
A subscription to the paging network works the following way:
- You get assigned your own ‘RIC’, which is publicly broadcast with every message
- You get assigned a private number (0665xxxxxx)
- While your subscription is active, you send an SMS or an e-mail to a specific address with your private number + message, and the network provider will broadcast it with the RIC as the recipient.
Then, anyone who knows your private number is able to reach a pager listening to your RIC. The public RIC is not enough information to request a message to be sent to you.
Registering to the network has a monthly cost (typical current pricing of 8 € - 20 €) depending on whether you want to be able to recieve text messages, numeric messages, or only make the pager beep. Your identity and banking information are known to the network provider. I was able to register as an individual without needing to provide any company information. I had to fill-in a short form and send it over e-mail with a photo of an ID to register.
So:
- The network provider knows your identity
- The service has a monthly cost
- The unencrypted message content, when they are sent, and the recipient’s RIC are public information
- The network does not confirm delivery
- Inefficient for the network (all transmitters broadcast every message)
- Being a legacy system, the network may not remain alive for too long
But:
- It is possible to reach you at all times without needing to broadcast your location to the network
The pager is a technology that I looked at early on when I started thinking about privacy and I quickly discarded the idea. Giving my identity to a network provider and broadcasting unencrypted messages publicly did not seem logical to me.
Today, I see the value of having a receive-only device that is supported by a network with national coverage. A paging message would contain only enough information for me to know how urgently I need to find a way to communicate - whether I need to activate the burner phone immediately, or whether I can spend some time to go find another way to communicate.
For me, it was a pleasant surprise to discover that this legacy system fills the specific gap of reachability without tracking.
I also recently became aware of the existence of paging networks that rely on volunteer HAM radio operators (like DAPNET), and would like to explore these systems in the future.
Neat!
This is a really cool write up! :D
Excellent write up
Thank you
Big thanks OP for the read,
You don’t see posts like this on lemmy every day and I’m grateful to have seen this one
Thank you for reading! Happy you find it valuable.
This is so cool, yet another great advantage of the Netherlands.
I think that the Dutch make some good/interesting infrastructure choices.
LoRA is sort of a slower version of wifi and as such, you should assume Meshtastic is monitored, at least for traffic metadata. The actual messages are encrypted though.
Use of ham radio for this type of thing, or with any type of encryption, is against the ham regulations, though depending on how it is done it could be made hard to detect.
There is actually still such a thing as a satellite pager, a receive-only device that can get pages that cover regions as big as small countries. They stopped making the receivers quite a while back, but some are still around and the subscriptions are still available, though expensive. This info is itself some years old so maybe they are all gone by now.
POCSAG pagers still exist in the US too, though again, they are quite expensive compared to cell phones. Their main attraction is supposed to be higher reliability, so e.g. doctors can get paged even with the mobile phone network is out. I don’t know if that advantage still exists. In the more distant past there was something called ARDIS which I think is gone now. That was quite a robust signal, so you could get paged even in sub-basements of buildings and places where mobile phones didn’t work. Repair technicians who worked in those places often carried them.
I’ve followed this stuff slightly as it’s interesting for the reasons you say, but I’d have to say it’s not really cost effective for most of us. POCSAG in particular only works in relatively localized areas like single countries. I know a guy who would want something like it, but only if it worked pretty much everywhere, since he travels a lot.
LoRA is sort of a slower version of wifi and as such, you should assume Meshtastic is monitored, at least for traffic metadata. The actual messages are encrypted though.
LoRa is great in that it gives us direct control and ownership over the infrastructure. One can participate in the network without their identity being known. But, yes, traffic metadata specifying the sender and recipient identifiers are plain text and can be easily logged.
Default configurations will have your device broadcasting often to contact new neighbors and will re-broadcast incoming messages. Since the device is quite active, and the chirped signal signal so characteristic when seeing via an SDR, someone who is actively tracking a Meshtastic device can do so very effectively.
Still, the fact that you own fully the device and have total control over it opens up a lot of possibilities. To give one example: if the mesh around here were strong, I could make use of a device configured for Rx only as a meshtastic pager. I might set up my Raspberry pi to inject a message from a randomized sender via MQTT in response to an XMPP message. Then, I would not use any radio transmitter at all.
For regular peer-to-peer chatting, yes, the default properties are very leaky, but we can change some of what we don’t like.
There is actually still such a thing as a satellite pager, a receive-only device that can get pages that cover regions as big as small countries. They stopped making the receivers quite a while back, but some are still around and the subscriptions are still available, though expensive. This info is itself some years old so maybe they are all gone by now.
That is very interesting. When I looked into satellite devices I only found two way devices, like the GARMIN inReach. I figured that it made sense that satellite comms would be 2-way because broadcasting all over the world seems rather extreme.
I have searched for these now and found the Iridium 9501 from Motorola. It is pricey, ~$680 for the device and either $90 (150 messages) or $150 (unlimited) per month for the subscription. In the description it says that you do need to program three ‘Message Delivery Areas’ as the messages are not broadcast globally, but I think this is acceptable.
Thanks for pointing that out. $90/month is pricey… But it is cool enough that I would seriously consider it if I would travel a lot for work.
POCSAG pagers still exist in the US too, though again, they are quite expensive compared to cell phones. Their main attraction is supposed to be higher reliability, so e.g. doctors can get paged even with the mobile phone network is out. I don’t know if that advantage still exists. In the more distant past there was something called ARDIS which I think is gone now. That was quite a robust signal, so you could get paged even in sub-basements of buildings and places where mobile phones didn’t work. Repair technicians who worked in those places often carried them.
I think that the advantage might still exist, especially in buildings with thick walls and underground floors. While looking into pagers I found discussions about them being phased out in many hospitals and replaced with ‘EPIC secure chat’ and with sharing private cellphone numbers.
In the Netherlands there is also the P2000 system, which is considered to be very reliable. That network makes use of FLEX to send messages to emergency services. It is possible to easily capture those too using SDR, or to see a live dump of these messages in sites like this one: https://p2000-online.net/alleregiosf.html
I’ve followed this stuff slightly as it’s interesting for the reasons you say, but I’d have to say it’s not really cost effective for most of us. POCSAG in particular only works in relatively localized areas like single countries. I know a guy who would want something like it, but only if it worked pretty much everywhere, since he travels a lot.
Yea, I can see that. So, that guy might like the satellite pager, but probably will not like the price tag.
Thanks for your reply!
Yea, I can see that. So, that guy might like the satellite pager, but probably will not like the price tag.
No he didn’t like the satellite pager because it didn’t have enough coverage. He wanted it to work worldwide. The cost was also an issue. And I don’t know if they work well indoors.
Wait, phone companies still offer pager plans? TIL
I recently tuned in with SDR in the US and was able to hear multiple hospitals.
Some of it was even HIPPA leaks. Patient names, condition.
I confirmed this with my own SDR years ago after seeing a presentation about it at DEFCON.
Yes, at least in the Netherlands. I was also surprised to discover this.
Cool experiment.
Last I heard they’re still heavily used in hospitals and prisons, though that is pre-covid intel now
Hospitals yes. They’re cheap and reliable. For doctors, you don’t need anything more than “get to the hospital”. You can call in on your cell phone if you want to get more info or give instructions on your way in. And it’s a lot easier to get that tiny message across in low-signal areas.
What? why!?
Someone with better knowledge correct me if I’m wrong, but:
Hospitals because you don’t need to interact with the pager to see the message it’s beeping about (the doctor’s hands may be occupied and/or they want the quickest possible response)
Prisons because if a prisoner got hold of a receive-only pager, it’s a lot less of a problem than if they get a two-way phone
You mentioned meshtastic, and that’s what I was thinking as soon as I saw the title of your post, the Liligo T-Deck would seem to be just about the exact same thing, except that it would allow two-way communications and encrypted.
But I do get what you mean about not being able to be reliably reached with it since it’s only 3-hop normal and 7-hop maximum, and that’s likely not enough to cover a large, large area like a nation.
Airline passengers with nodes are amazing repeaters for the few minutes they are overhead. Thanks to them I’ve seen signals hop to my nodes from nearly 200 miles away
It’s crazy how fast meshtastic/lora technologies have taken off in just a few years
I actually hate those. If you’re in a moving vehicle of any sort, you should be in client mute mode so that you do not connect people that otherwise would not be able to be connected.
An airplane is out of signal range far too quickly and just inundates your node with nodes you will never ever be able to speak with again.
Something like a high altitude drone would be alright, because that could be stationary. But a plane? No.
That’s fair, I think it’s cool because I have so few people in range normally.
People have put nodes on essentially a weather balloon and that had cool results
I can understand doing that for tracking the balloon, but even still, that probably should also have been in client mute.
You’ve also got to consider how much battery relaying all that traffic would use extra.
I live in one of the most densely-packed Meshtastic cities in the US. It is indeed very cool to message back and forth with my buddy several miles away on community-owned infrastructure.
I have nearly the exact opposite problem. I live in a city and we have a router that’s up at 200 feet, but it has went down. I guess wind got to the antenna or something like that. And that’s the only connection I had to the wider mesh. And so, right now, I’ve got nothing.
When the local router was still working though, I would generally have anywhere between about 6 and 10 nodes normally.
Just because I’m all alone though does not mean I’m giving up. I figure either our router will come back online when it’s fixed or the mesh will densify to the point where I start to get another connection by something. So I’m just waiting.
I do like Meshtastic a lot and I am still trying to get the most out of it. But there are too many gaps around here. In the city there are more nodes, but also a lot of buildings. Outside of the city there is more line of sight but few nodes.
I suspect that will improve as time goes on and more and more people get nodes.
Just as an example, when I first got my node back in January, I only saw 3500 nodes on the mesh map, and now I frequently see about 7000. Mind you, that’s worldwide, and 7,000 isn’t a whole lot of nodes for a worldwide network, but it’s definitely growing fairly quickly, and it’s not being put up by some infrastructure provider, like your telecom, it’s being done by normal people, so you can expect it to take a bit longer.
Also, I am fully aware that 7,000 is just the amount of people who have chosen to be shown on the map. Not the total number of nodes, but it gives you a decent idea.
I suspect so too. I contribute to the local network with a few nodes :) In a controlled, coordinated setting it works well, but continuous reliability and coverage are still challenging.
Excellent read
I assume the pager plan is pretty affordable too compared to cell phone data plans
Yeah, as others mentioned, you can get cheaper data plans depending on the monthly data you need.
However, one of the interesting properties is that, unlike with phones, there is no restriction on the number of pagers that can listen to your assigned RIC. You can use one subscription to communicate with as many pagers as you would like, and each individual pager can be programmed using text filters such that one can implement their own sub-address system.
Cell phone data is fairly low priced in the EU compared to the US…I used to pay $17/month for 50GB data and 5G access, and I could use 10GB of that without extra charge in all EU countries. I’ve reduced my plan now to 10GB/month because i wasn’t using more than that, and it costs $10/month
That doesn’t sound better then the plans in the US. I currently get unlimited data for $15/month.
Ah OK fair enough, I’ve just seen so many from the US cite ridiculous cell phone plans
Canada is the expensive plan place
