The Punkt MP02 (previously) is one of two or three premium-yet-minimalist phone handsets that actually work on post-2G cellular networks. And now it has Signal built-in, providing end-to-end voice encryption, free-Internet based calls and texts, group messages and voice dictation. From a press release:
The MP02 is the first voicephone to offer a downloadable privacy feature that uses the Signal protocol to provide free, encrypted Internet-based calls and texts worldwide via Wi Fi or mobile data (subject to data charges). Signal provides vastly greater security compared to the widely-used encrypted alternatives, which exist primarily as tools for harvesting and selling valuable metadata (contacts lists, who communicated with whom, when it happened, etc.). In the Signal system, all metadata is encrypted.
The Signal system also adds group messaging and voice messages to the MP02.
Just remember: less is more to pay.