[ac29]

Seems like it'd be a plausible (small) business idea. A $10 SDR stick with a piece of wire as an antenna is enough to pick up pager signals, and I doubt you'd need a much more advanced setup to transmit. A 100 or 400 MHz license in the US costs maybe $500 for a decade. Mounted at the right spot, you wouldnt need much power to cover a large area with a single transmitter, though basements are always going to be trouble.

[ornornor]

> A $10 SDR stick with a piece of wire as an antenna is enough

That doesn’t sound like mission-critical levels of reliability.

[ac29]

My point was the technology is cheap - there are certainly better dedicated, inexpensive chips that could be used to make a simple wireless messaging system.