Assuming you're OK with moving to an internet connection for replies, FLEX pagers are a reasonable way to receive alerts. You can even do something nutty like p

Assuming you're OK with moving to an internet connection for replies, FLEX pagers are a reasonable way to receive alerts. You can even do something nutty like put an SMS/MMS gateway on an android phone, with notification or encrypted messages delivered 'last mile' over the pager network. I dream of a device with WiFi, LTE, and FLEX, with the ability to power on/off each subsystem individually.