HN Explorer

CLI via SMS

7 points by shanebellone ↗ HN
Short Clip: https://www.youtube.com/shorts/DFi03pC_lt0

I recently bought a GSM Modem to build a local SMS service. The modem interface is written in Python and implements and processes raw Hayes (AT) commands/response. CLI over SMS is just a toy demo.

I can send "unlimited" SMS for $20/m (Google Fi). However, GSM protocol requires 3-6 seconds per message. So "unlimited" is actually quite limited.

Anyone else playing with modems in 2023?

4 comments

[ 2.1 ms ] story [ 25.0 ms ] thread
f0e4c2f7
Wow this is actually amazing. I would have never thought to try something like this. A fun thought that comes to mind is connecting docker and twillio on the other end and then offering some kind of a pay per text vm for randomly testing things. Not sure if anyone would use that.

The fact that you got it to work at all is very entertaining to me.

shanebellone
I appreciate that!

My plan is to connect the SMS service to a self-hosted endpoint. The first test app was a grocery list manager that adds or removes items and returns the whole list on command.

I find text messaging convenient and wanted to leverage it as an interface.

Edit: I love learning and acquiring new skills even if they aren't immediately useful. It's part of a compounding knowledge process I started years ago.

mdmglr
A while ago I ran into a listing on Ali Express that was selling a large board that interfaced with a computer over USB. The board was I think essentially a USB Hub where you would host a dozen or more GSM Modems.

Here is one example: https://www.aliexpress.us/item/2251832290676842.html

My guess is this is for mostly outbound traffic. I don't know how this would work for incoming. As you probably want users to text with a single number.

I would be interested in trying this out for fun. What model modem are you using?

Some ideas this could be useful for:

1. If you run a home server this could be used as a signaling mechanism for restarts, open/close ports, etc.

2. Control your home automation if internet is down.

shanebellone
"The board was I think essentially a USB Hub where you would host a dozen or more GSM Modems."

That's an interesting form factor. I'm using a traditional USB dongle.

"What model modem are you using?"

ZTE MF833V 4G LTE. You can plug many USB dongles into a USB hub and operate dozens of sim cards. Although the link you shared would likely be more affordable.

"Some ideas this could be useful for..."

I do run a home server, and I plan on using this for home automation! I'm also building a home assistant with an SMS interface. I love the simplicity of the medium.

"I would be interested in trying this out for fun."

I'm testing and compiling the Hayes commands that apply to GSM modems. The process isn't bad once you figure which commands to use and in which order. If you're interested, I can link you to the document once its finished. It took me 2 weeks to find the right commands and get them working.

Any particular reason for your interest or just an opportunity to learn something new?