Most providers let you email phone numbers to send an SMS. I don't know if your LEO phone would. However, when I attempted it every "from" was a different rando

Most providers let you email phone numbers to send an SMS. I don't know if your LEO phone would. However, when I attempted it every "from" was a different random provider phone number (fewer digits than normal) Keep in mind SMSs are pretty rate/bandwidth limited in your use case. SMSs originally (and probably still in your case) were based on having 140 bytes of freeish data in the keep-alive style pings between tower and phone. So you only get/send one SMs per (on regular devices I believe this is no longer the case). Can you program the device you will be using, or does it need to be human readable? One solution might be to run a cloud SMS service. You can set up an SMS endpoint on AWS with bidirectional communication. It would let you write as complex code as you would like to generate/parse the SMSs, and probably falls into almost free at a personal scale. As a warning as someone who built a little SMS autosender (as I said earlier based on email), be careful you don't accidentally DoS yourself. Consider some way to turn it off. Constantly getting texts on a device without the ability to assign a specific ringtone because the event you was sure was rare happened more frequently was no fun until I changed the code.