Summary

Adds bidirectional Telnyx Media Streaming support to the realtime voice path so users can run sub-second-latency voice on Telnyx + a realtime LLM (Gemini Live, OpenAI Realtime, etc.) end-to-end. Previously realtime.enabled: true required provider: "twilio"; this lifts that restriction by adding the small amount of provider-specific transport plumbing Telnyx needs (it negotiates the stream via the streaming_start Call Control action rather than via TwiML).

The same RealtimeCallHandler WebSocket bridge serves both providers. Telnyx and Twilio Media Streams use a near-identical wire format (event: "media" with base64 audio, clear, mark, stop); the only differences are inbound field names (stream_id/call_control_id vs streamSid/callSid) and the fact that Telnyx emits a connected frame before start. Both shapes are now accepted.

Layered changes

• Validation (extensions/voice-call/src/config.ts): provider !== "twilio" becomes provider !== "twilio" && provider !== "telnyx" when realtime.enabled is true.
• Provider contract (extensions/voice-call/src/providers/base.ts + types.ts): adds optional startMediaStream / stopMediaStream methods + StartMediaStreamInput / StopMediaStreamInput shapes. Twilio doesn't implement them; its TwiML path is unchanged.
• Telnyx provider (extensions/voice-call/src/providers/telnyx.ts): implements startMediaStream (issues streaming_start with stream_bidirectional_mode: "rtp" + stream_bidirectional_codec: "PCMU" defaults) and stopMediaStream (idempotent streaming_stop via allowNotFound).
• Manager hook (extensions/voice-call/src/manager.ts): adds setRealtimeStreamStarter which fires on call.answered for non-TwiML realtime providers.
• Realtime handler (extensions/voice-call/src/webhook/realtime-handler.ts): WS handler now ignores Telnyx's connected frame and accepts either Twilio (start.streamSid / start.callSid) or Telnyx (top-level stream_id / start.call_control_id) start-event shapes. Adds mintStreamUrl() so non-TwiML providers can construct the wss URL.
• Runtime wiring (extensions/voice-call/src/runtime.ts): wires the manager's stream-starter callback for any provider with startMediaStream. Includes a per-call dedup set so that providers (notably Telnyx) which fire call.answered twice — once for their auto-answer and once for our explicit answer POST — only issue one streaming_start. The dedup is reset on failure so retries still work.

Codec choice

Default is PCMU 8 kHz (mu-law) to match the existing audio pacer (extensions/voice-call/src/webhook/realtime-audio-pacer.ts), which encodes the Live model's PCM output to 8 kHz mu-law for Twilio Media Streams. Telnyx accepts the same shape, so realtime providers work over Telnyx with no resample changes. StartMediaStreamInput exposes codec + samplingRate overrides for callers that prefer L16 16 kHz (recommended by Telnyx for AI integrations) once a higher-rate audio pacer lands.

Verification

• pnpm test extensions/voice-call extensions/google — 21 test files / 206 tests pass, including 6 new tests:
  • config.test.ts — accepts telnyx + realtime; still rejects plivo + realtime
  • providers/telnyx.test.ts — startMediaStream defaults; track/codec/sampling-rate overrides; stopMediaStream idempotent cleanup
  • webhook/realtime-handler.test.ts — mintStreamUrl returns null without public origin and a fresh-token wss URL with one; WS handler accepts Telnyx connected + start { stream_id, call_control_id } shape
• pnpm tsgo --project tsconfig.extensions.projects.json — clean
• pnpm exec oxfmt --check on all 10 changed files — clean

Real behavior proof

Behavior or issue addressed: Realtime voice mode (realtime.enabled: true) previously required provider: "twilio"; users on Telnyx had no path to sub-second voice latency. This PR wires Telnyx's streaming_start Call Control action and the WebSocket dialect into the same RealtimeCallHandler bridge that Twilio uses, so realtime voice now works on Telnyx end-to-end. Also fixes a call.answered double-fire from Telnyx that, without dedup, would issue two streaming_start commands per call.

Real environment tested: OpenClaw gateway 2026.5.7 running locally on Linux 6.17 (Ryzen AI Max+ 395), patched voice-call plugin in realtime mode, provider: "telnyx", realtime.provider: "google" → Gemini Live model gemini-2.5-flash-native-audio-preview-12-2025, real Telnyx number +1 (651) 422-0083 with bidirectional media streaming over an ngrok WebSocket tunnel (stretch-unclaimed-foe.ngrok-free.dev). Inbound calls placed from a real US cell phone over PSTN.

Exact steps or command run after this patch:

1. Apply the 10-file patch and restart the gateway: openclaw gateway restart
2. Confirm realtime is wired: journalctl --user -u openclaw-gateway -n 50 | grep "Realtime voice provider" should show Realtime voice provider: google
3. Place a live inbound call from a real cell phone to the Telnyx number
4. Ask a tool-needing question (consult tool) on the call to exercise the full realtime + agent path
5. Tail the gateway during and after the call: journalctl --user -u openclaw-gateway -f | grep -E "voice-call|telnyx call|realtime"
6. Confirm the per-call dedup gate: only one Starting realtime media stream line per call, even though Telnyx fires call.answered twice

Evidence after fix: Redacted runtime logs from journalctl --user -u openclaw-gateway during a real live call. The Starting realtime media stream for telnyx call ... -> wss://... line is the new code path (extensions/voice-call/src/runtime.ts stream-starter wiring → extensions/voice-call/src/providers/telnyx.ts:startMediaStream); Realtime bridge starting is the existing RealtimeCallHandler.handleCall accepting Telnyx's stream_id + start.call_control_id shape that this PR added support for; realtime tool call/realtime tool result lines are real openclaw_agent_consult round-trips through the openclaw agent.

[voice-call] Inbound call accepted: policy is open
[voice-call] Created inbound call record: ac17e818-6054-4237-8565-387deabed891 from +16127153507
[voice-call] Starting max duration timer (300s) for call ac17e818-6054-4237-8565-387deabed891
[voice-call] Starting realtime media stream for telnyx call ac17e818-6054-4237-8565-387deabed891 -> wss://stretch-unclaimed-foe.ngrok-free.dev/voice/stream/realtime/00ff8eb3-c37d-4686-b390-1f78c980e39e
[voice-call] Realtime call ac17e818-6054-4237-8565-387deabed891 initial greeting queued
[voice-call] Realtime bridge starting for call ac17e818-6054-4237-8565-387deabed891 (providerCallId=v3:4fgmlWVhG5JZ1X44GfI9WC-cKZGkJP-IQjPOgHPZWmr0D3X7WNlCdw, initialGreeting=queued)
[voice-call] realtime tool call: name=openclaw_agent_consult callId=ac17e818... args={"question":"How many prospects are currently in the system?"}
[voice-call] realtime tool result: name=openclaw_agent_consult callId=ac17e818... ms=4493 result={"text":"I currently have 67 prospects in the system, though one is a test entry and should be ignored."}

Observed result after fix: Inbound Telnyx phone calls connect to the realtime bridge over the bidirectional WebSocket, the caller hears the model's greeting within ~1 second of pickup, and the conversation runs full-duplex with sub-second voice turn latency. Tool calls round-trip through the full openclaw agent (openclaw_agent_consult) in 3.5–9 seconds with the existing working-on-it filler bridging the gap. Per-call dedup observed: exactly one Starting realtime media stream line per real call even with Telnyx's two call.answered events. Zero regressions observed on the Twilio realtime path during the same session.

What was not tested: Outbound calls from openclaw to a real PSTN destination via Telnyx (only inbound was exercised; outbound shares the same code path but the dial is initiated by provider.initiateCall which is unchanged); the L16/16000 codec/samplingRate overrides on StartMediaStreamInput (only the PCMU/8 kHz default was exercised because the existing realtime audio pacer is locked to mu-law/8 kHz today); Plivo realtime (Plivo provider does not implement startMediaStream so the new wiring no-ops there, but no Plivo number was on hand to confirm).

Sources

• Telnyx — Media Streaming over WebSockets
• Telnyx — Bi-directional streaming release notes
• Telnyx — Streaming start API