Exotel

Run assistant-api with Exotel for PSTN voice calls in India and South-East Asia.

Exotel is a cloud telephony provider for India and South-East Asia. It follows the same webhook → WebSocket pattern as Twilio: Exotel calls your server when a call arrives, Rapida responds with passthru XML that opens a WebSocket media stream.

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Vault Credentials

In the Rapida dashboard go to Credentials → Create Credential, select provider type Exotel:

Key	Description
api_key	Exotel API key
api_secret	Exotel API secret
account_sid	Exotel Account SID

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Setup

1. Set PUBLIC_ASSISTANT_HOST

   PUBLIC_ASSISTANT_HOST is the public HTTPS hostname Exotel will use to reach your server — for webhooks and the WebSocket media stream.

   Production

   Set it in docker/assistant-api/.assistant.env:

   PUBLIC_ASSISTANT_HOST=your-server.com   # no https:// prefix
   

   Also update connection.media in ui/src/configs/config.production.json:

   {
     "connection": {
       "media": "https://your-server.com"
     }
   }
   

   Local Development (ngrok)

   Exotel’s servers originate from India/SEA and cannot reach localhost. Use ngrok to create a public HTTPS tunnel:

   1. Install and authenticate ngrok

   # macOS
   brew install ngrok/ngrok/ngrok
   
   # Linux
   curl -sSL https://ngrok-agent.s3.amazonaws.com/ngrok.asc \
     | sudo tee /etc/apt/trusted.gpg.d/ngrok.asc >/dev/null
   echo "deb https://ngrok-agent.s3.amazonaws.com buster main" \
     | sudo tee /etc/apt/sources.list.d/ngrok.list
   sudo apt update && sudo apt install ngrok
   
   ngrok config add-authtoken <your-authtoken>
   

   Get your authtoken at dashboard.ngrok.com.

   2. Start the tunnel (keep this running)

   ngrok http 8080
   # Forwarding  https://abc123.ngrok-free.app -> http://localhost:8080
   

   3. Update two files with the ngrok hostname

   File	Field	Value
   docker/assistant-api/.assistant.env	PUBLIC_ASSISTANT_HOST	abc123.ngrok-free.app (no https://)
   ui/src/configs/config.development.json	connection.media	https://abc123.ngrok-free.app (with https://)

   # docker/assistant-api/.assistant.env
   PUBLIC_ASSISTANT_HOST=abc123.ngrok-free.app
   

   // ui/src/configs/config.development.json
   {
     "connection": {
       "media": "https://abc123.ngrok-free.app"
     }
   }
   

   4. Rebuild

   make rebuild-assistant
   

   Exotel may have higher latency to ngrok tunnels depending on region. For best results during testing, use an ngrok region closest to Exotel’s traffic origin (India): ngrok http 8080 --region=in (if available on your plan).

2. Configure the ExoPhone app

   In Exotel Dashboard → ExoPhones, select your ExoPhone and assign it an App. Set the passthru URL to:

   https://{PUBLIC_ASSISTANT_HOST}/v1/talk/exotel/call/{assistantId}?x-api-key={apiKey}
   

   Replace {assistantId} with the numeric assistant ID from the Rapida dashboard.

3. Attach vault credential to the assistant

   In the assistant’s Phone Deployment, select the Exotel vault credential.

4. Verify

   curl https://{PUBLIC_ASSISTANT_HOST}/readiness/
   # Expected: {"status":"ok"}
   

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What Rapida Returns

When Exotel hits the webhook, Rapida returns passthru XML that connects a WebSocket at:

wss://{PUBLIC_ASSISTANT_HOST}/v1/talk/exotel/ctx/{contextId}?x-api-key={apiKey}

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Audio Spec

Property	Value
Encoding	μ-law (PCMU) 8-bit
Sample rate	8000 Hz
Channels	Mono

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Twilio

Global PSTN alternative

Vonage

Higher audio quality (16kHz)

Telephony Overview

All providers and URL routing reference

Configuration

Full env var reference