Smart Routing

Smart Routing is Zavu's system that automatically selects the optimal channel for each message, maximizing delivery rates while minimizing costs.

When Smart Routing Applies

How It Works

For outbound messages, the router checks if the contact has previously messaged you:

CodeCopy
Has contact messaged via WhatsApp in last 24h?
      |
   +--+--+
   |     |
  Yes   No
   |     |
   v     v
WhatsApp    WhatsApp only
available   with template
(preferred)

Since WhatsApp is cheaper than SMS, the router prefers WhatsApp when the 24-hour window is open.

Channel Selection Algorithm

The router evaluates channels in this order:

1. Filter viable channels: Remove channels that can't deliver (e.g., WhatsApp without open window)
2. Sort by cost: Cheapest channels first
3. Check success rate: Channel must have at least 80% success rate (or fewer than 3 attempts for exploration)
4. Select best option: First channel meeting all criteria

Cost Optimization

Smart routing can reduce messaging costs by up to 80% by preferring WhatsApp when available.

WhatsApp 24-Hour Window

WhatsApp has a strict rule: you can only send free-form messages within 24 hours of the last message received from the contact.

CodeCopy
Contact sends message ... 24-hour window opens
      |
Within 24h: Send any message type
      |
After 24h: Only template messages allowed

Channel Metrics

Zavu tracks delivery metrics for each contact and channel:

JSONCopy
{
  "channelMetrics": {
    "sms": {
      "successCount": 45,
      "failureCount": 2,
      "avgDeliveryTimeMs": 3200,
      "lastSuccessAt": "2025-01-15T10:30:00Z"
    },
    "whatsapp": {
      "successCount": 120,
      "failureCount": 1,
      "avgDeliveryTimeMs": 1100,
      "lastSuccessAt": "2025-01-15T14:22:00Z"
    }
  }
}

The router uses these metrics to:

• Avoid channels with low success rates (below 80%)
• Prefer faster channels when speed matters
• Explore new channels (first 3 attempts get a chance regardless of stats)

Automatic Fallback

When a message fails on one channel, Zavu automatically retries on an alternate channel.

Fallback Flow

CodeCopy
Send via WhatsApp
      |
      v
  Failed?
      |
   +--+--+
   |     |
  No    Yes
   |     |
   v     v
Done   Wait 5s
         |
         v
   Retry via SMS
         |
         v
     Success?
         |
      +--+--+
      |     |
     Yes   No
      |     |
      v     v
   Done   Mark Failed

Fallback Rules

Tracking Fallback

A message that fell back keeps its id and reports the channel it was finally sent on:

JSONCopy
{
  "id": "msg_abc123",
  "status": "delivered",
  "channel": "sms"
}

In this example, the message first tried WhatsApp, failed, and was delivered via SMS.

Fallback is on by default only when Zavu picks the channel. A send with an explicit channel does not fall back unless it sets fallbackEnabled: true; see Senders.

Manual Override

To bypass Smart Routing for a specific message, specify the channel explicitly:

TypeScriptcURLCopy
await zavu.messages.send({
  to: "+56912345678",
  text: "This must go via SMS",
  channel: "sms"
});

Best Practices

Next Steps