Absolutely anyone else who has goTenna within range of you.
The reason you can't chat with people who don't have goTenna is due to the physics of radio waves. You need a properly designed RF receiver to interpret a goTenna signal. We would love to have our signals get to devices that aren't goTenna-enabled, but phones are designed to work with towers — exactly what we are working around — and regular radios aren't able to operate at the level of our super-smart networking protocols (plus, are analog radios, while we are a cognitive digital radio).
With that said, the goTenna Plus app upgrade enables an SMS network relay feature, so you can reach people beyond your off-grid network. If a goTenna user nearby has cell service, they can transmit your message via SMS to your intended recipient.
TL;DR: We're the first and only ones doing this! #innovation :)