Not counting vehicle to vehicle, up until recently, nothing. I've threatened to get a sat phone forever but never did. My sister worries about me and got me a Garmin Mini 2.
I can text her my GPS or a short message. It works ok. Mine interfaces with my phone. I text using that. The model before mine didn't interface with a phone so, older ones are not very good. Sometimes it wont let me send a custom text and I have to use one of their pre made "I'M safe" messages.
