Ringless Voicemail API Integration Guide

Drop Cowboy's API lets you integrate ringless voicemail, SMS, and voice broadcast directly into your applications. This guide covers the key concepts for successful integration.

Prerequisites:

• Drop Cowboy account with API access
• API key from your account dashboard
• Basic understanding of REST APIs
• Development environment for your preferred language

Authentication:

All API requests require authentication via API key header:

Authorization: Bearer YOUR_API_KEY

API keys are generated in your Drop Cowboy dashboard under Settings > API. Keep your API key secure and never expose it in client-side code.

Sending a Ringless Voicemail

POST /api/v1/campaigns/ringless
Content-Type: application/json
Authorization: Bearer YOUR_API_KEY

{
  "contacts": [
    {
      "phone": "+15551234567",
      "first_name": "John",
      "custom_fields": {
        "property_address": "123 Main St"
      }
    }
  ],
  "message_id": "msg_abc123",
  "caller_id": "+15559876543",
  "scheduled_at": "2026-01-15T10:00:00Z"
}

Response:

{
  "campaign_id": "camp_xyz789",
  "status": "queued",
  "contacts_count": 1,
  "estimated_delivery": "2026-01-15T10:05:00Z"
}

Checking Campaign Status

GET /api/v1/campaigns/{campaign_id}
Authorization: Bearer YOUR_API_KEY

Response:

{
  "campaign_id": "camp_xyz789",
  "status": "completed",
  "stats": {
    "total": 1,
    "delivered": 1,
    "failed": 0,
    "pending": 0
  }
}

Configure webhook URLs in your Drop Cowboy dashboard to receive real-time updates about your campaigns.

Delivery Status Webhook

POST https://your-app.com/webhooks/dropcowboy
Content-Type: application/json
X-DC-Signature: sha256=...

{
  "event": "message.delivered",
  "campaign_id": "camp_xyz789",
  "contact": {
    "phone": "+15551234567",
    "external_id": "your_contact_123"
  },
  "timestamp": "2026-01-15T10:05:23Z",
  "metadata": {
    "carrier": "verizon",
    "region": "us-east"
  }
}

Webhook Event Types:

• message.delivered - Message successfully delivered to voicemail
• message.failed - Delivery failed (includes reason)
• message.pending - Message queued for delivery
• contact.opted_out - Contact requested opt-out
• contact.callback - Contact called back (if tracking enabled)

Verifying Webhook Signatures:

Always verify the X-DC-Signature header to ensure webhooks are from Drop Cowboy. See our developer documentation for signature verification code examples.

Batch Operations

For optimal performance, batch your operations where possible instead of making individual calls. Group contacts into campaigns rather than sending individual requests for each message.

Error Handling

Implement proper error handling for all API calls:

• 400 errors: Fix request payload issues
• 401 errors: Check API key validity
• 429 errors: Implement backoff and retry
• 500 errors: Retry with exponential backoff

Idempotency

Use unique external IDs for contacts and campaigns to prevent duplicate sends. The API uses these IDs to deduplicate requests if your retry logic fires multiple times.

Testing

For development and testing, use test phone numbers from your own contacts with their consent. Production API requests are live, so validate your integration thoroughly before launching campaigns. Start with small batches to verify proper operation.

Logging

Log all API requests and responses for debugging. Include campaign IDs, timestamps, and status codes. This data helps troubleshoot issues and optimize performance.

Security

Never expose API keys in client-side code or public repositories. Rotate keys periodically. Use separate keys for development and production environments.