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Voice Call (plugin)

Voice calls for Pllan via a plugin. Supports outbound notifications and multi-turn conversations with inbound policies. Current providers:
  • twilio (Programmable Voice + Media Streams)
  • telnyx (Call Control v2)
  • plivo (Voice API + XML transfer + GetInput speech)
  • mock (dev/no network)
Quick mental model:
  • Install plugin
  • Restart Gateway
  • Configure under plugins.entries.voice-call.config
  • Use pllan voicecall ... or the voice_call tool

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Where it runs (local vs remote)

The Voice Call plugin runs inside the Gateway process. If you use a remote Gateway, install/configure the plugin on the machine running the Gateway, then restart the Gateway to load it.

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Install

pllan plugins install @pllan/voice-call
Restart the Gateway afterwards.

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Option B: install from a local folder (dev, no copying)

pllan plugins install ./extensions/voice-call
cd ./extensions/voice-call && pnpm install
Restart the Gateway afterwards.

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Config

Set config under plugins.entries.voice-call.config: 
{
  plugins: {
    entries: {
      "voice-call": {
        enabled: true,
        config: {
          provider: "twilio", // or "telnyx" | "plivo" | "mock"
          fromNumber: "+15550001234",
          toNumber: "+15550005678",

          twilio: {
            accountSid: "ACxxxxxxxx",
            authToken: "...",
          },

          telnyx: {
            apiKey: "...",
            connectionId: "...",
            // Telnyx webhook public key from the Telnyx Mission Control Portal
            // (Base64 string; can also be set via TELNYX_PUBLIC_KEY).
            publicKey: "...",
          },

          plivo: {
            authId: "MAxxxxxxxxxxxxxxxxxxxx",
            authToken: "...",
          },

          // Webhook server
          serve: {
            port: 3334,
            path: "/voice/webhook",
          },

          // Webhook security (recommended for tunnels/proxies)
          webhookSecurity: {
            allowedHosts: ["voice.example.com"],
            trustedProxyIPs: ["100.64.0.1"],
          },

          // Public exposure (pick one)
          // publicUrl: "https://example.ngrok.app/voice/webhook",
          // tunnel: { provider: "ngrok" },
          // tailscale: { mode: "funnel", path: "/voice/webhook" }

          outbound: {
            defaultMode: "notify", // notify | conversation
          },

          streaming: {
            enabled: true,
            streamPath: "/voice/stream",
            preStartTimeoutMs: 5000,
            maxPendingConnections: 32,
            maxPendingConnectionsPerIp: 4,
            maxConnections: 128,
          },
        },
      },
    },
  },
}
Notes:
  • Twilio/Telnyx require a publicly reachable webhook URL.
  • Plivo requires a publicly reachable webhook URL.
  • mock is a local dev provider (no network calls).
  • Telnyx requires telnyx.publicKey (or TELNYX_PUBLIC_KEY) unless skipSignatureVerification is true.
  • skipSignatureVerification is for local testing only.
  • If you use ngrok free tier, set publicUrl to the exact ngrok URL; signature verification is always enforced.
  • tunnel.allowNgrokFreeTierLoopbackBypass: true allows Twilio webhooks with invalid signatures only when tunnel.provider="ngrok" and serve.bind is loopback (ngrok local agent). Use for local dev only.
  • Ngrok free tier URLs can change or add interstitial behavior; if publicUrl drifts, Twilio signatures will fail. For production, prefer a stable domain or Tailscale funnel.
  • Streaming security defaults:
    • streaming.preStartTimeoutMs closes sockets that never send a valid start frame.
    • streaming.maxPendingConnections caps total unauthenticated pre-start sockets.
    • streaming.maxPendingConnectionsPerIp caps unauthenticated pre-start sockets per source IP.
    • streaming.maxConnections caps total open media stream sockets (pending + active).

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Stale call reaper

Use staleCallReaperSeconds to end calls that never receive a terminal webhook (for example, notify-mode calls that never complete). The default is 0 (disabled). Recommended ranges:
  • Production: 120–300 seconds for notify-style flows.
  • Keep this value higher than maxDurationSeconds so normal calls can finish. A good starting point is maxDurationSeconds + 30–60 seconds.
Example: 
{
  plugins: {
    entries: {
      "voice-call": {
        config: {
          maxDurationSeconds: 300,
          staleCallReaperSeconds: 360,
        },
      },
    },
  },
}

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Webhook Security

When a proxy or tunnel sits in front of the Gateway, the plugin reconstructs the public URL for signature verification. These options control which forwarded headers are trusted. webhookSecurity.allowedHosts allowlists hosts from forwarding headers. webhookSecurity.trustForwardingHeaders trusts forwarded headers without an allowlist. webhookSecurity.trustedProxyIPs only trusts forwarded headers when the request remote IP matches the list. Webhook replay protection is enabled for Twilio and Plivo. Replayed valid webhook requests are acknowledged but skipped for side effects. Twilio conversation turns include a per-turn token in <Gather> callbacks, so stale/replayed speech callbacks cannot satisfy a newer pending transcript turn. Example with a stable public host: 
{
  plugins: {
    entries: {
      "voice-call": {
        config: {
          publicUrl: "https://voice.example.com/voice/webhook",
          webhookSecurity: {
            allowedHosts: ["voice.example.com"],
          },
        },
      },
    },
  },
}

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TTS for calls

Voice Call uses the core messages.tts configuration for streaming speech on calls. You can override it under the plugin config with the same shape — it deep‑merges with messages.tts. 
{
  tts: {
    provider: "elevenlabs",
    elevenlabs: {
      voiceId: "pMsXgVXv3BLzUgSXRplE",
      modelId: "eleven_multilingual_v2",
    },
  },
}
Notes:
  • Microsoft speech is ignored for voice calls (telephony audio needs PCM; the current Microsoft transport does not expose telephony PCM output).
  • Core TTS is used when Twilio media streaming is enabled; otherwise calls fall back to provider native voices.

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More examples

Use core TTS only (no override): 
{
  messages: {
    tts: {
      provider: "openai",
      openai: { voice: "alloy" },
    },
  },
}
Override to ElevenLabs just for calls (keep core default elsewhere): 
{
  plugins: {
    entries: {
      "voice-call": {
        config: {
          tts: {
            provider: "elevenlabs",
            elevenlabs: {
              apiKey: "elevenlabs_key",
              voiceId: "pMsXgVXv3BLzUgSXRplE",
              modelId: "eleven_multilingual_v2",
            },
          },
        },
      },
    },
  },
}
Override only the OpenAI model for calls (deep‑merge example): 
{
  plugins: {
    entries: {
      "voice-call": {
        config: {
          tts: {
            openai: {
              model: "gpt-4o-mini-tts",
              voice: "marin",
            },
          },
        },
      },
    },
  },
}

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Inbound calls

Inbound policy defaults to disabled. To enable inbound calls, set: 
{
  inboundPolicy: "allowlist",
  allowFrom: ["+15550001234"],
  inboundGreeting: "Hello! How can I help?",
}
inboundPolicy: "allowlist" is a low-assurance caller-ID screen. The plugin normalizes the provider-supplied From value and compares it to allowFrom. Webhook verification authenticates provider delivery and payload integrity, but it does not prove PSTN/VoIP caller-number ownership. Treat allowFrom as caller-ID filtering, not strong caller identity. Auto-responses use the agent system. Tune with:
  • responseModel
  • responseSystemPrompt
  • responseTimeoutMs

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CLI

pllan voicecall call --to "+15555550123" --message "Hello from Pllan"
pllan voicecall start --to "+15555550123"   # alias for call
pllan voicecall continue --call-id <id> --message "Any questions?"
pllan voicecall speak --call-id <id> --message "One moment"
pllan voicecall end --call-id <id>
pllan voicecall status --call-id <id>
pllan voicecall tail
pllan voicecall latency                     # summarize turn latency from logs
pllan voicecall expose --mode funnel
latency reads calls.jsonl from the default voice-call storage path. Use --file <path> to point at a different log and --last <n> to limit analysis to the last N records (default 200). Output includes p50/p90/p99 for turn latency and listen-wait times.

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Agent tool

Tool name: voice_call Actions:
  • initiate_call (message, to?, mode?)
  • continue_call (callId, message)
  • speak_to_user (callId, message)
  • end_call (callId)
  • get_status (callId)
This repo ships a matching skill doc at skills/voice-call/SKILL.md.

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Gateway RPC

  • voicecall.initiate (to?, message, mode?)
  • voicecall.continue (callId, message)
  • voicecall.speak (callId, message)
  • voicecall.end (callId)
  • voicecall.status (callId)