This is so cool. I will always try to support any project that takes mobile computing/communications in a more libre, hackable, privacy-respecting direction.

However, I don't buy the argument for WiFi only. Sure, you are often on WiFi... But if I wanted to make a private VoIP call in such locations, I would just use my Linux laptop (or, realistically, any computer).

The reason for having a phone like this is for essential communication on the go -- not just to be an application specific piece of hardware.

That said, they have to start somewhere and I'm sure LTE integration is a lot of work. It's cool just to have something like this being developed. Keep it up!