Hi everyone,
I wanted to share a small open source project I built with Retell.
I restored a Siemens S62 (“Bigrigio”), a classic Italian desk phone, and connected it to a Raspberry Pi Zero 2 W so it can place and receive live AI phone calls through Retell using pjsua/SIP.
What it currently does:
- hook detection via GPIO
- starts a Retell SIP call when the handset is lifted
- hangs up when the handset is placed back down
- ALSA audio routing on Raspberry Pi
- local WAV recording for debugging
- systemd autostart support
This was especially fun for me because I’m mainly a backend engineer, not an electronics expert, and this was my first time really opening up and rewiring a vintage analog phone like this 
Repo: https://github.com/Fabryz/siemens-s62-retell-phone
Write-up: https://medium.com/@fabryz/from-a-flea-market-siemens-s62-to-an-ai-phone-204b35eacc12
Still improving:
- rotary dial support
- better microphone placement inside the handset
- cleaner volume / audio tuning
If this fits better in another category, feel free to tell me and I’ll move it
