Yes, that’s an SMS text messaging device. [Mdziewie] decided that texting on a regular cellphone was too boring and decided to build himself an old-school SMS gateway. Here’s a translated link but the formatting of the forum post gets screwed up with the machine translation.
The device he’s using is an ASR-33 Teletype machine, which was introduced to the market in 1963. It is connected to a GSM modem via an ARM microcontroller, the STM32F103. This chip, along with a few electronic components, let [Mdziewie] design an interface that doesn’t require alteration to the ancient hardware. The forum post linked above includes video of this sending and receiving texts. It’s awesomely loud as it hammers away at the paper, and seems to work as expected.
If you hunger for one of your own but don’t have half-century old equipment there’s still hope. Find yourself a typewriter and turn it into a teletype machine.