
It’s good enough for what I need as is. I was thinking about doing something like this with an esp32, IIRC there’s a voip firmware for the esp. I was thinking of hiding it in the rotary phone along with a battery, connecting it to the mobile network via a hotspot or just setting the esp32 up like a BT headset. Then put the rotary in a backpack and using it to receive a call on the commuter train or so.

4x sims. Thank the gods you were not caught in Russia.
(If you don’t know what I’m taking about google for “russia sims nazi”)