Android GMS Kotlin Integration

I need an Android GSM app that stays always running and connects to my Next.js web app to stream real-time audio both ways.

Flow:
- Website connects to Android phone over Wi-Fi
- Android phone makes / receives real GSM calls (SIM)
- Call audio is streamed to the website
- Website audio is injected into the live GSM call
- Full-duplex, low-latency audio.

Requirements:
- Android app in Kotlin
- Foreground service, auto-start
- GSM call control + audio routing
- WebRTC for real-time audio
- Node.js / signaling integration
- Asterisk knowledge is a big plus

Stack
Web: Next.js, Node.js, TypeScript (my side)
Android: Kotlin, WebRTC
VoIP: WebRTC, possibly Asterisk

Notes:
This is not a VoIP app

It’s a GSM ↔ Web audio gateway
You’ll work alongside me (I handle web/backend)

Repo (prototype):
https://github.com/nicitaacom/AndroidGSM