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Show HN: A pager

udp7777.com

104 pointskeepamovin43 comments

Hello HN,

I basically don't use notifications for anything. The noise is too much. Slack is too loud. Email is too slow. But sometimes you do need a note in your face.

I found myself missing 1990s pagers. I wanted a digital equivalent - something that does one thing: beep until I ack it.

So I built UDP-7777.

Concept:

- 0% Cloud: It listens on UDP Port 7777. No accounts, no central servers. You don't need Tailscale/ZeroTier/WG/etc, it's just easy for device sets.

- CAPCODES: It maps your IP address (LAN or Tailscale) to a retro 10-digit "CAPCODE" that looks like a phone number (e.g., (213) 070-6433 for loopback).

- Minimalism: Bare-bones interface. Just a box, a few buttons, and a big red blinker.

The Tech:

It's a single binary written in Go (using Fyne). It implements "burst fire" UDP (sending packets 3x) to ensure delivery without the handshake overhead of TCP.

New in v2.2.7:

- Frequency Tuning: Bind specifically to your Tailscale/ZeroTier interface.

- Squelch: Optional shared-secret keys to ignore unauthorized packets.

- Heartbeat: Visual/Audio alerts that persist until you physically click ACK.

I built this for anyone looking to cut through the noise—DevOps teams handing off the "on-call IP", or deep-work focus where you only want interruptions from a high-trust circle.

I'd love to hear your thoughts on the IP-to-Phone-Number mapping logic (it's purely visual, but I'm really into it).

Site & Binaries (Signed for Mac/Win): https://udp7777.com

Open articleView on HN

>I found myself missing 1990s pagers.

I still use one which gets one-way service from <https://pagersdirect.net/> (~$14/mo, with phone number and pager included). Most US cities, large and small, still have active infrastructure. I live in a city with a few hundred thousand people, great coverage.

This has replaced my mobile phone, which I no longer carry. It also prevents spammers from messaging... because the systems don't understand this antiquated technology [1].

For those interested, Pagers Direct has an email-to-pager option (I don't use it, phone digits only please caller, after the beep). It also has two-way pagers, which I have no experience with.

One caution: for one-way pagers, if you're out of range[0] when somebody sends you text, you will never get the message (no handshake/confirmation).

[0] does not use traditional cellular infrastructure

[1] TBH: most humans don't either, unless you explain how to page somebody: key in your callback#/code after the beep [no audio/text]

[•] I don't work for the above-linked paging service, I'm just a very happy customer.

That is so cool. I really want to get one (or make a hardware company that builds simple, DIY kits for them).

With a prepaid annual subscription, they sent me a pager for FREE.

>builds simple, DIY kits for them

So I highly doubt this would be profitable for you.

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As far as the paging infrastructure is concerned, all the messages are mass-sent, in an un-encrypted analogue broadcast. EVERY device receives EVERY page, as long as within range. It is the pager itself which chooses to only display "your" message(s).

Your DIY hardware could lead you into some interesting discoveries of your local area's messaging/users.

Yep, 20-odd years ago, I had modified a radio scanner and added a discrete output. Then used Poc32 to decode pager messages from the scanner via the PC’s sound card.

Got lots of server health messages and requests to call people back. And some more personal messages, too.

That is the exact vibe I wanted to capture. The feeling of a raw, unencrypted signal that just "appears" without a handshake. It felt more alive than a JSON payload over HTTPS.

>Got lots of server health messages and requests to call people back. And some more personal messages, too.

That vibe is reflected in the 9/11 pager messages as well... https://911.wikileaks.org/

Also had a pager up until 2023 (when I was on call). If you're in range is an awesome tool to use. Great for alerts, ironically I had it hooked up to SMS with PagerDuty.

Really neat project, see my sister comment (on analogue pagers still in service).

>I'd love to hear your thoughts on the IP-to-Phone-Number mapping logic (it's purely visual, but I'm really into it).

Personally, this seems like a really bad idea. The similarity to actual phone numbers might lead to confusion by non-technical high-trust contactors. Worse (e.g.) if the IP were 91.1x.x.x then this could lead to further confusion &/or erroneous 9-1-1 misdials (by inept contactors).

It's a UDP packet, ought it not be in IP-format?

>where you only want interruptions from a high-trust circle

I don't even have a phone contact number anymore. After you page me, I'll VoIP you back from an outbound-only.

But overall I LOVE that you have attempted this; only real problem for your average installer/recipient is that most home ISPs are firewalled (so a UDP7777 inbound isn't possible), but this obviously isn't for even your average technical installer.

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Just leave me alone, world/SPAMmers!

How do you prevent malicious actors from invading your 7777UDPs?

For anti-spam, the general use case is use of Tailscale/Zerotier where you are in control of your network. If you are on public internet and have 7777 open then you can use the Squelch filter under the CFG page. It drops every message that doesn't start with your secret::

> It drops every message that doesn't start with your secret::

Depending on how internet-proof you want to make this, I wonder if it might be better to sign with a secret and attach the signature to the message instead of directly sending the secret.

I considered that! But thought for this “first public” release it might be overkill. Definitely one of the possibilities for later

Woah! The world really works in mysterious ways. I've found myself thinking in this space a lot recently. I've been working on a pager that takes the notifications from my phone and relays only the ones I want to see. I use LTE-M/NB-IOT to get connectivity anywhere and the device works and I'm looking to find a way to get a pcd/case made..

Landing page (doesn't link to anything): https://fob.launchbowl.com/

A little word dump of thoughts at the start of the journey: https://launchbowl.com/e_ink_pager

Your project seems really cool and allows you to bring your own hardware. Out of curiosity, have you blocked all notifications on your phone? Would this be run on your computer? Would you ever move in the direction of a physical device?

I'd love to get a real pager again too. But not LTE-M based because that's still a two way system so I can be traced.

I just have a pretty strong desire to get my anonymity back when I want it. Not because I need it but just to feel free again.

US: <http://www.pagersdirect.net>

I have and use one, partially for the reasons you list above.

[•] Not a representative of the company, just a very happy customer.

I'm in Spain, unfortunately there's apparently not s single pager network remaining :( Some other EU countries still have them but not here.

Thanks for the tip though!

Heh, that is exactly why I kept UDP-7777 passive. It listens on 0.0.0.0 but sends zero telemetry and requires no "online" status packet. Unless you hit ACK (which sends a packet back), you are a ghost.

Yes! I really want a physical device for things like this. It's cool we are both thinking about it: independent invention. That is a sick website. Love the design!

I am also here for an LTE-M pager… I have no POCSAG coverage anywhere near me… that would be a very nice little design.

Just took another look at your work, and your LTE-M project looks incredible. The e-ink aesthetic is exactly right for this. I've fantasized about building some apps for e-ink displays (wanted to drop BrowserBox in a remarkable tablet, etc), but haven't yet. Here I stuck to desktop/software for v1 to solve the immediate 'screen fatigue' issue, but I'd love to see a world where physical tokens like yours replace the smartphone notification center.

Yes, I block all the notifications on the phone. I leave badges for some apps and check when I want, or just periodically check when it's in my rhythm. (A few people have exceptions). It runs on computer now, but the next step is I want to test if mobile could be achieved without a server (I'm okay with a Tailscale/ZT requirement or such, for now). Aside from that I would love physical infra. If it could work such that it piggy-backed off existing infra, at first, might be good approach. Someone should do this. I don't know if it's us, but it should be created.

If anyone would like to discuss these possibilities, please reach out at pager@dosaygo.com

As someone who builds and operating a very large simulcast paging network for emergency services I can assure you POCSAG is not completely legacy ;-) very much alive and well in 2025.

Definitely old but highly reliable.

Inhowfar were you able to harden such a legacy protocol against state-actor attacks on critical infrastructure? Is it a legacy protocol in the sense of simple & robust or spoofable & floodable?

Edit: To clarify, if the frequency is known couldn't they simply disable/jam all devices?

The area covered in question is over 200km2. Might be hard to imagine how much RF transmission/reception equipment we have in that space.

An attacker would need a lot of fairly powerful jamming equipment just to disrupt a small area of it. And our customer would advise us pretty quickly if their personnel were having reception issues and our field engineers would diagnose the source of the interference pretty quickly. So no.

Thanks for elaborating. Is there an extension to the protocol so it frequency hops once jammed?

This arrived at the perfect time! I was discussing pagers with my friend a few days back, after he expressed annoyance at me always being offline :. unavailable, unless I made the active choice to check my notifications (something I do not enjoy at all).

Timing is everything!

Do you have this running on some kind of pager shaped device? What do you use it for?

finger is better (and best is reticulum)

or https://shop.exploitee.rs/shop/p/the-hacker-pager

Really cool. I like the flashing red.

Thanks. I thought I should not just use a sound in case people are deaf or don't have volume on.

Good but I want POCSAG-compatible radio version like DAPNET

If you’re OK with plugging in an RTLSDR we could probably figure this out

I will send my thoughts but at which number?

What is "UDP-7777"? Is it some kind of software? What does it do exactly?

You should check out the website.

The website does not say anything. The website offers me to download a .zip file. Why should I download a .zip file? As far as I know, a pager is supposed to be a physical object?

Is the source available? What is presented is a machine-generated website with very little meaningful information and mystery binaries for three platforms.

PS: The "SHA256 CHECKSUMS VERIFIED." is static. No hash check is performed, and as far as I can see the website doesn't have a list of hashes to check.

Thanks for this caution / opsec.

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Public WhoIS registrant:

Chris [redacted]

The Dosyago Corporation

Beaverton, Oregon

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OP has ~2 year old /hn/ account, with ~11k karma

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I have made no further investigations, but obviously haven't installed this myself (as I have an IRL pager that solves similar issues to OP's).

There's also an operator manual if you're looking for more info: https://www.udp7777.com/usage.html

> The Protocol

> The system is intentionally raw. No headers, no JSON, no XML.

> Transport: UDP Port 7777

> Encoding: UTF-8 Plain Text

> Format: [SECRET::]MESSAGE

you dont get it, the protocol is flawless

There is another component to the protocol,

> Only messages matching your Secret Key will ring.

I assume that's the "Secret Key" is placed in this prefix tag, '[SECRET::]' ?

Since plain-text over UDP is not very secret, I'm now motivated to look into how Wireguard is able to use PKI to only accept packets from a trusted clients. And, how that protocol could be used to generate the Secrey Key.

Raw packets never lie.

I normally work on larger projects (BrowserBox, dn), and now believe in new release methods which is why the source is closed.

Your radar was okay: site is machine-generated by build workflow which pushes the binaries. The "Verified" label reflects internal CI attestation, but without public hashes? Might cause concern. Did not consider, tho based on your comment I've now replaced with "Digitally Signed and Notarized".

So reflects more accurately how the binaries are always digitally signed and notarized (Apple Developer ID + Microsoft Authenticode) with our company certs. SOP for my releases. The verification is the cryptographic signature checked by your OS kernel, not just a text file.

I actually like this presentation better now!

Signing, notarization, and hash checking just ensures that what I run is the thing that you meant for me to run. Source availability permits me to ensure that what I run is the thing that I meant to run.

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