If people are showing off a lab. My lab always sparks a conversation. I wanted to prove I could beat twilio's texting rates. https://i.imgur.com/gKknrJn.jpg
Back in the day you would walk into a rooms filled with racks full of phones for SMS / Airtime sales "optimisation".
I tried to google some pictures now but it turns out Im behind the times. They've gotten rid of the phone part completely! [0]
Now you just buy the sim cards and let modems do the rest..
[0] http://modempool.net/wp-content/uploads/2016/05/2-jual-alat-...
This is really intriguing.
I'm currently running a SFF machine as a server, and thought about adding some Pi devices to play around with a local kubernetes cluster.
It actually did work for a while. The problem that you run into is that carriers rate limit the number of texts per minute that a particular phone number can send (this is a problem with Twilio too, but in that case it's much easier to spin up a new number).
The problem with texting rates isn't technical, it's that carriers essentially have a cartel and can set prices however they want, and have tools to detect and prevent such "abuse" of their cheap consumer plans for commercial usage.
"and have tools to detect and prevent such abuse" <- This was my assumption too. I tested all large carriers. Verizon, however doesn't seem to have these limits in place. With a verizon sim I can push out about 200 texts per hour per device. If you get rejected in my tests depends on the receiving carrier.
"it's that carriers essentially have a cartel and can set prices however they want" <- yes. Carrier to carrier is where things are interesting. Sprint gets quickly blocked by ATT for example. But, wow, a UNLIMITED TEXT plan is pretty cheap...