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.

Abstract

The evolution of adaptive innovations carries strong eco-evolutionary implications, allowing organisms to explore novel ecological opportunities, which facilitates lineage diversification. The remarkable diversity of reproductive strategies in amphibians provides a natural laboratory for identifying ecological mechanisms driving evolutionary novelties. In viviparous salamanders, the transition from larviparous (i.e., live bearing of aquatic larvae) to pueriparous (i.e., live bearing of fully terrestrial juveniles) reproduction is hypothesized to represent an adaptation to the absence of water for larval deposition, in what is known as the dry-climate hypothesis. This work aimed to identify the ecological drivers of independent evolutionary transitions to pueriparity and test the dry-climate hypothesis.

Main Conclusions

Reproductive transitions to pueriparity in salamanders were consistently associated with scarcity of surface water driven by steep topography and karstic geology, providing the most unambiguous support for the dry-climate hypothesis to date and supporting convergent evolution of terrestrialisation in salamanders for most pueriparous lineages. Climatic, hydrological (i.e., soil moisture and vapour pressure deficit) and habitat factors appear to be comparatively less relevant drivers of reproductive shifts, yet may have played a role in specific transitions to pueriparity, especially at the intraspecific level. We also found key differences in the use of available habitat between reproductive modes, with pueriparity representing a more specialised strategy likely restricted to areas with strong selective pressure against aquatic breeding.

This is a recent article that describes some details on the reproductive biology of Bolitoglossa pandi. I found it interesting to see how the eggs are deposited as clutches among leaf litter.

The article also includes this nice image of Bolitoglossa hatchlings:

A new species of salamander from Costa Rica, Bolitoglossa chirripoensis, has been described!

KLANK, JEREMY, et al. "A new species of salamander of the genus Bolitoglossa (Caudata: Plethodontidae) from the highest massif of the Cordillera de Talamanca, Costa Rica." Zootaxa 5642.5 (2025): 427-450.

Research Gate Link

There are a few people out there self-dosing with snake venom. The posted article is based on a study on the blood of one of these guys, Tim Friede, who has developed very effective antivenom in his blood after 20 years of self-dosing with a diverse array of snake venoms.

Vice did a few documentaries on Steve Ludwin, who is also self-immunizing. In one of these he answers questions about how he began and his motivation for doing what he does. In addition to producing anti-bodies he also believes that snake venoms have medicinal and anti-ageing properties - but these beliefs do not appear to be supported by any animal-based data as far as I can tell: https://www.youtube.com/watch?v=AcbqB0pFRPA

Self-dosing with snake venom is not something I would recommend. Generally a bad idea. But it is interesting to see the results and to learn about what motivates someone to do something like this.

Abstract

Bolitoglossa digitigrada Wake, Brame and Thomas, 1982 was described from a few kilometers upstream from the Rio Santa Rosa, Ayacucho Region, Peru, at 1000 m a.s.l. in the Eastern Amazonian Montane Forest. Besides the type specimens, no additional collections or sightings of B. digitigrada had been reported for 43 years, and there is no information about its phylogenetic position inside its group. During a field expedition conducted in October 2022, we found four individuals of B. digitigrada in a corn and banana field near the community of San Jose, approximately 2.7 km from the type locality. Here, we provide information about living specimens, update description of coloration in life, elevation, and evaluate the phylogenetic relationships of B. digitigrada with a molecular phylogeny based on a 16S rRNA sequence.

This is a Trachycephalus typhonius, formerly Trachycephalus venulosus, from Yucatan.

These frogs secrete a sticky and irritant milk-like fliud through its skin when bothered. Several years ago I got some some of that fluid into my eyes by accident - that hurts similar to scratching one's eye after touching a spicy pepper. So, they are not terribly toxic but I certainly do not recommend the experience.

Funnily enough I just ran a search and found a publication of someone who describes a similar but worse experience: https://www.thebhs.org/publications/the-herpetological-bulletin/issue-number-152-summer-2020-1/3101-09-a-caution-on-handling-i-trachycephalus-venulosus-i-anura-hylidae-toxic-effects-of-skin-secretion-on-human-eyes/file

You may notice that the finger pads of this frog look green. That's because its bones are green! A characteristic feature of this species. Here is a photo (not mine) of a skeleton of one of these : https://www.pybio.org/wp-content/uploads/2008/06/t-ven31.jpg

A new paper on a Bolitoglossid showed up in my alerts today! 🥳

It is a one-pager and comes with a beautiful photo of a foraging arboreal salamander 😄

Found this Imantodes cenchoa sleeping on top of a leaf in Punta Laguna, Quintana Roo.

Here is a photo of where it was sleeping:

There are a few different snakes of the genus Imantodes in Yucatán. What sets this species apart is that the row of scales on its back consists of enlarged scales. Here is a closeup emphasizing that row of scales. The green arrow points at an enlarged mid-dorsal scale, the blue arrow at a regular scale.

In comparison, here is a photo from an Imantodes tenuissimus that I took back in 2009 in Mérida, Yucatán (with a less sharp camera), and a closeup of its mid-dorsal scales that does not show this enlargement.

One of my favorite frogs! Spent some time specifically looking for it. Managed to find two near Cobá, in Quintana Roo (in the Yucatán peninsula). This frog hides in holes in lime stone and tree trunks, and makes use of its flat head to block the entrance. This type of defense is known as phragmosis.

Some other shots: