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Customnewupdated May 19, 2026 · telecom · support

Telephony voice agent with inbound and outbound call handling

A minimal bridge connecting Twilio Programmable Voice to the AssemblyAI Voice Agent API. Handles both inbound and outbound phone calls with zero audio transcoding by using G.711 μ-law passthrough. Includes tool calling example (generate random number) and automatic barge-in support. Demonstrates how to build a telephony voice agent that answers calls, speaks first on outbound dials, and executes function calls.

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The numbers

latency—

cost / min—

frameworkCustom

The stack

telephonyTwilio Voice

speech-to-textAssemblyAI Streaming

llmGPT-4o

text-to-speechElevenLabs Turbo v2.5

System prompt

No prompt published.

Config

config.json

{
  "voice_id": "ivy",
  "barge_in": true,
  "tools": [
    {
      "name": "generate_random_number",
      "description": "Generates a random number as a sample tool call"
    }
  ],
  "audio_format": "audio/pcmu",
  "sample_rate_hz": 8000
}

Tools

generate_random_numberGenerates a random number as a sample tool call

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