Real AI voice calls on a linked Android phone
9 real projects, 4 architectures, one recommended stack
A linked Android phone can carry real two-way AI voice calls today. The blocker is call audio: Android exposes no API for in-call uplink/downlink audio. Every working project escapes that limit one of four ways.
The pick
"This phone: no root route"
- Linked device: moto g play - 2024 (fogona), Android 14, build U1TFS34.100-35-14-1-21.
- Bootloader is locked: ro.boot.flash.locked = 1, verifiedbootstate = green.
- gsm2sip and Zerkat need root, so they cannot run on this device.
- No-root pick: Bluetooth HFP bridge to a Linux box, then any SIP agent.
Why call audio is the hard part
Stock Android gives apps no access to live call audio. Each route moves that audio across a different boundary, with different setup cost.
Nine real projects
| Project | Route | Root | Note |
|---|---|---|---|
| pulpoff/gsm2sip | Phone as GSM↔SIP gateway | yes | active 2026, calls + SMS |
| telon-org/react-native-gsm-sip-gateway | Same, SIMBox lineage | yes | legacy codebase |
| Zerkat | Commercial Android SIP↔SIP-GSM app | yes | supported product |
| bg111/asterisk-chan-dongle | Huawei USB stick as Asterisk trunk | classic, cheap hardware | |
| PipeWire 1.4 telephony | Linux box pairs as HFP hands-free | call control + audio, new in 2025 | |
| santisbon/iphonebridge | Working HFP bridge daemon | reference: BlueZ + oFono + PipeWire | |
| asterisk/AsteriskVoiceBridge | Official Asterisk AI framework (ARI + external media) | n/a | demo grade, AGPL |
| k2-fsa/sherpa-onnx | On-device ASR/TTS for a local agent | mature, runs offline | |
| kirklandsig/AIReceptionist | OpenAI Realtime + LiveKit SIP receptionist | n/a | self-hosted SIP-side agent |
The Allternit stack (no root)
Outbound: the agent sends a dial command over HFP; the phone places the cellular call. The SIP agent (LiveKit SIP, AsteriskVoiceBridge, AIReceptionist) can run on the box or behind it.
If you will not root the phone
"Two no-root paths, one extra box"
- Pair the phone to a Linux box (a Pi works) over Bluetooth HFP.
- PipeWire 1.4+ carries call audio and call control to the box.
- macOS cannot act as an HFP hands-free unit natively; use Linux.
- Alternative: auto-answer + speakerphone + sherpa-onnx agent on the phone. Expect echo and lower quality.
Verdict
"The AI line is already live"
- Telnyx numbers take calls in both directions today.
- Inbound: carrier SIP to LiveKit; the voice agent answers with live transcripts.
- Outbound dialing works; caller ID shows the Allternit number.
- Call UI: transcript, Listen and Take over, on all three surfaces.
"Linked-phone voice: wired build in progress"
- Stock Android exposes no call-audio API; software alone cannot put the bot on the phone line.
- Rejected 2026-10-18: call forwarding, root, Bluetooth HFP, iPhone Continuity.
- Chosen: a wired USB-C audio kit per phone; six workstreams are building now.
- Future option: a curated rooted-device tier could run a GSM-to-SIP gateway without cables.