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.
Just slap a mosfet in between the modem and ringer so you can boost the signal with an external power supply.
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.