Vapi + n8n workflow: Outbound voice announcements with auto-end. Send a short voice message (loyalty reminder, appointment alert, billing notification) and auto-terminate the call. Uses dynamic Vapi controlUrl per call session. Built by Rinshin Jalal.

README.md

Vapi Outbound Announcement + Auto Hangup

Simple outbound announcement flow using Vapi.

Perfect for:

• loyalty/reward reminders
• appointment reminders
• billing notifications
• delivery alerts
• pharmacy pickup notifications

The customer does not need to speak.

The flow:

1. Start outbound call
2. Play announcement
3. Automatically hang up after playback finishes

---

Flow Overview

Create outbound call
    ↓
Get monitor.controlUrl from response
    ↓
Send "say" control message
    ↓
endCallAfterSpoken: true
    ↓
Call automatically ends

---

Step 1 — Create the Outbound Call

curl 'https://api.vapi.ai/call' \
  -H 'authorization: Bearer YOUR_API_KEY' \
  -H 'content-type: application/json' \
  --data-raw '{
    "assistantId": "YOUR_ASSISTANT_ID",
    "customer": {
      "number": "+12345678913"
    },
    "phoneNumberId": "YOUR_PHONE_NUMBER_ID"
  }'

---

Example Response

{
  "id": "7420f27a-30fd-4f49-a995-5549ae7cc00d",
  "assistantId": "5b0a4a08-133c-4146-9315-0984f8c6be80",
  "phoneNumberId": "42b4b25d-031e-4786-857f-63b346c9580f",
  "type": "outboundPhoneCall",
  "createdAt": "2024-09-10T11:14:12.339Z",
  "updatedAt": "2024-09-10T11:14:12.339Z",
  "customer": {
    "number": "+12345678913"
  },
  "status": "queued",
  "monitor": {
    "listenUrl": "wss://aws-us-west-2-production1-phone-call-websocket.vapi.ai/7420f27a-30fd-4f49-a995-5549ae7cc00d/transport",
    "controlUrl": "https://aws-us-west-2-production1-phone-call-websocket.vapi.ai/7420f27a-30fd-4f49-a995-5549ae7cc00d/control"
  }
}

Use:

monitor.controlUrl

for the next step.

---

Step 2 — Send the Announcement

curl -X POST 'CONTROL_URL_FROM_PREVIOUS_RESPONSE' \
  -H 'content-type: application/json' \
  --data-raw '{
    "type": "say",
    "content": "Hello, you currently have 100 unused points within our supermarket rewards program. Please redeem them soon. Thank you, goodbye.",
    "endCallAfterSpoken": true
  }'

---

What Happens

The call will:

• play the announcement
• automatically hang up afterward
• never wait for customer input

No conversational flow required.

---

Why This Approach?

This is much cleaner than building a full conversational assistant when you only need:

• one-way announcements
• reminders
• notifications

Benefits:

• lower latency
• lower cost
• no transcription needed
• no interruption handling
• CRM-friendly
• automation-friendly

Works well with:

• n8n
• Make.com
• Zapier
• GoHighLevel
• HubSpot
• custom CRMs

---

Production Tips

Add a Small Delay Before Control

Sometimes the call is not fully connected immediately after creation.

Adding a small delay improves reliability:

2–5 second delay

before sending the control request.

---

Dynamic CRM Variables

Example dynamic message:

Hello John, you currently have 143 unused points. Please redeem them before expiration. Thank you, goodbye.

Perfect for:

• loyalty systems
• clinics
• insurance reminders
• payment alerts

---

Example n8n Flow

Webhook / CRM Trigger
    ↓
Create Vapi Call
    ↓
Wait 3 Seconds
    ↓
POST monitor.controlUrl
    ↓
Auto Hangup

---

Important Notes

• Use monitor.controlUrl dynamically from each call response
• Do NOT hardcode websocket/control URLs
• endCallAfterSpoken: true automatically terminates the call

---

Useful Docs

• https://docs.vapi.ai/calls/call-features
• https://docs.vapi.ai/calls/voicemail-detection
• https://docs.vapi.ai/calls/customer-join-timeout

---

Built after watching multiple people accidentally turn a 20-second supermarket announcement into a distributed AI orchestration platform.

An industry tradition.

vapi-outbound-announcement-n8n-workflow.json

{
  "name": "Vapi Outbound Announcement Flow",
  "nodes": [
    {
      "parameters": {
        "httpMethod": "POST",
        "path": "vapi-announcement",
        "options": {}
      },
      "id": "da34565f-8461-4144-ac91-2b802a285831",
      "name": "Webhook",
      "type": "n8n-nodes-base.webhook",
      "typeVersion": 1,
      "position": [
        496,
        -32
      ],
      "webhookId": "vapi-announcement"
    },
    {
      "parameters": {
        "method": "POST",
        "url": "https://api.vapi.ai/call",
        "sendHeaders": true,
        "headerParameters": {
          "parameters": [
            {
              "name": "authorization",
              "value": "Bearer YOUR_VAPI_API_KEY"
            },
            {
              "name": "content-type",
              "value": "application/json"
            }
          ]
        },
        "sendBody": true,
        "specifyBody": "json",
        "jsonBody": "{\"assistantId\":\"5b0a4a08-133c-4146-9315-0984f8c6be80\",\"customer\":{\"number\":\"{{$json.phone}}\"},\"phoneNumberId\":\"42b4b25d-031e-4786-857f-63b346c9580f\"}",
        "options": {}
      },
      "id": "e93dcbe6-1a6e-40f7-b258-dcc752549997",
      "name": "Create Call",
      "type": "n8n-nodes-base.httpRequest",
      "typeVersion": 4,
      "position": [
        720,
        -32
      ]
    },
    {
      "parameters": {
        "amount": 3,
        "unit": "seconds"
      },
      "id": "b45f7188-a7f2-4982-a2c9-59e23f7abace",
      "name": "Wait",
      "type": "n8n-nodes-base.wait",
      "typeVersion": 1,
      "position": [
        944,
        -32
      ],
      "webhookId": "0a079011-eb45-472a-941b-d5e92dc9ed08"
    },
    {
      "parameters": {
        "values": {
          "string": [
            {
              "name": "callId",
              "value": "={{$node[\"Create Call\"].json[\"id\"]}}"
            },
            {
              "name": "name",
              "value": "={{$node[\"Webhook\"].json[\"name\"]}}"
            },
            {
              "name": "controlUrl",
              "value": "={{$node[\"Create Call\"].json[\"monitor\"][\"controlUrl\"]}}"
            }
          ],
          "number": [
            {
              "name": "points",
              "value": "={{$node[\"Webhook\"].json[\"points\"]}}"
            }
          ]
        },
        "options": {}
      },
      "id": "abea84c7-f8af-487a-992f-affec169bd06",
      "name": "Prepare Data",
      "type": "n8n-nodes-base.set",
      "typeVersion": 2,
      "position": [
        1168,
        -32
      ]
    },
    {
      "parameters": {
        "method": "POST",
        "url": "={{$json.controlUrl}}",
        "sendHeaders": true,
        "headerParameters": {
          "parameters": [
            {
              "name": "content-type",
              "value": "application/json"
            }
          ]
        },
        "sendBody": true,
        "specifyBody": "json",
        "jsonBody": "{\"type\":\"say\",\"content\":\"Hello {{$json.name}}, you currently have {{$json.points}} unused points within our supermarket rewards program. Please redeem them soon. Thank you, goodbye.\",\"endCallAfterSpoken\":true}",
        "options": {}
      },
      "id": "c2efcc52-8984-4d71-bb65-d86397eccd20",
      "name": "Send Announcement",
      "type": "n8n-nodes-base.httpRequest",
      "typeVersion": 4,
      "position": [
        1392,
        -32
      ]
    }
  ],
  "pinData": {},
  "connections": {
    "Webhook": {
      "main": [
        [
          {
            "node": "Create Call",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Create Call": {
      "main": [
        [
          {
            "node": "Wait",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Wait": {
      "main": [
        [
          {
            "node": "Prepare Data",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "Prepare Data": {
      "main": [
        [
          {
            "node": "Send Announcement",
            "type": "main",
            "index": 0
          }
        ]
      ]
    }
  },
  "active": false,
  "settings": {
    "executionOrder": "v1",
    "binaryMode": "separate"
  },
  "versionId": "d680721f-4df6-44fe-9224-09c79c1283c4",
  "meta": {
    "instanceId": "8ec742a1f8e0781268e15b6e52fb83c50be6e4338b730b889bf1af4d81431605"
  },
  "id": "3WV8r1xfkKNb7aLx",
  "tags": []
}