Whatsapp Cloud API Reference

WhatsApp Messaging via Meta Cloud API

Overview

The Meta WhatsApp Cloud API is the official, fully hosted path for programmatic WhatsApp messaging. No server management needed. First 1,000 service conversations per month are free.

Key rules:

• Your app can NEVER send a free-form text message first. The very first message to any user must always be a pre-approved template. Free-form text is only unlocked after the user replies, and only within the 24-hour window that reply opens.
• Business-initiated messages outside a 24h reply window must use a pre-approved template
• Phone numbers must be registered in your WABA before sending
• Always use a System User token — user tokens expire in 24 hours

Conversation flow:

App → user:  MUST be a template (always, for first contact)
User → app:  reply opens a 24-hour free-form window
App → user:  free-form text allowed within that 24h window
  [24h passes with no user reply]
App → user:  MUST use a template again to re-engage

Setup Checklist

1. Create Meta Developer App — developers.facebook.com → Create App → Business type
2. Add WhatsApp product to the app (gives temp test number + 5 test recipient slots)
3. Create a permanent System User token:
   • Meta Business Manager → Settings → System Users → Create Admin user
   • Assign permissions: whatsapp_business_messaging + whatsapp_business_management
   • Generate token — this never expires
4. Register real phone number — number cannot already be active on personal/business WhatsApp
5. Set up webhook — needs public HTTPS URL (trusted CA cert, no self-signed), must respond in < 10s

Sending Messages

Text Message (Node.js)

// npm install axios
const axios = require('axios');

async function sendMessage(phoneNumber, text) {
    // phoneNumber: E.164 without +, e.g. "14155551234"
    const res = await axios.post(
        `https://graph.facebook.com/v21.0/${process.env.WA_PHONE_NUMBER_ID}/messages`,
        {
            messaging_product: 'whatsapp',
            recipient_type: 'individual',
            to: phoneNumber,
            type: 'text',
            text: { preview_url: false, body: text }
        },
        { headers: { Authorization: `Bearer ${process.env.WA_ACCESS_TOKEN}` } }
    );
    return res.data;
}

Text Message (Python)

# pip install requests
import requests, os

def send_message(phone: str, text: str) -> dict:
    r = requests.post(
        f"https://graph.facebook.com/v21.0/{os.environ['WA_PHONE_NUMBER_ID']}/messages",
        headers={"Authorization": f"Bearer {os.environ['WA_ACCESS_TOKEN']}"},
        json={
            "messaging_product": "whatsapp",
            "recipient_type": "individual",
            "to": phone,        # E.164 without +
            "type": "text",
            "text": {"preview_url": False, "body": text}
        }
    )
    r.raise_for_status()
    return r.json()

Quick test via curl

curl -X POST "https://graph.facebook.com/v21.0/YOUR_PHONE_ID/messages" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"messaging_product":"whatsapp","to":"14155551234","type":"text","text":{"body":"Hello"}}'

Template Message (required when > 24h since last user reply)

const payload = {
    messaging_product: 'whatsapp',
    to: phoneNumber,
    type: 'template',
    template: {
        name: 'hello_world',           // your approved template name
        language: { code: 'en_US' },
        components: [{
            type: 'body',
            parameters: [
                { type: 'text', text: 'John' },        // fills {{1}}
                { type: 'text', text: 'Order #4521' }  // fills {{2}}
            ]
        }]
    }
};

Media Messages (Image, Document, Audio, Video)

Image:

const payload = {
    messaging_product: 'whatsapp',
    to: phoneNumber,
    type: 'image',
    image: {
        link: 'https://your-domain.com/image.jpg'  // must be publicly accessible HTTPS
    }
};

Document:

const payload = {
    messaging_product: 'whatsapp',
    to: phoneNumber,
    type: 'document',
    document: {
        link: 'https://your-domain.com/file.pdf',
        caption: 'Invoice'  // optional
    }
};

Audio:

const payload = {
    messaging_product: 'whatsapp',
    to: phoneNumber,
    type: 'audio',
    audio: {
        link: 'https://your-domain.com/audio.mp3'
    }
};

Video:

const payload = {
    messaging_product: 'whatsapp',
    to: phoneNumber,
    type: 'video',
    video: {
        link: 'https://your-domain.com/video.mp4',
        caption: 'Demo video'  // optional
    }
};

Important constraints:

• All media URLs must be publicly accessible HTTPS (http:// fails)
• Max file sizes: Image 16MB, Document 100MB, Audio 16MB, Video 16MB
• Supported formats: Images (JPEG, PNG), Documents (PDF), Audio (AAC, MP3, OGG, WAV), Video (MP4, 3GPP)
• Media must not require authentication
• URLs cannot use shorteners (bit.ly, tinyurl, etc.)

Webhook Handler (Express) — Correct Async Pattern

// GET — Meta calls this to verify your endpoint
app.get('/webhook', (req, res) => {
    const { 'hub.mode': mode, 'hub.verify_token': token, 'hub.challenge': challenge } = req.query;
    if (mode === 'subscribe' && token === process.env.VERIFY_TOKEN)
        return res.status(200).send(challenge);  // raw string only — NOT JSON
    res.sendStatus(403);
});

// POST — CRITICAL: return 200 IMMEDIATELY, process async
app.post('/webhook', express.json(), (req, res) => {
    // Return 200 immediately so Meta doesn't retry
    res.sendStatus(200);

    // Process webhook payload asynchronously (don't block)
    setImmediate(() => {
        processWebhookAsync(req.body).catch(err => {
            logger.error(`Webhook processing failed: ${err.message}`);
        });
    });
});

async function processWebhookAsync(body) {
    body.entry?.forEach(entry =>
        entry.changes?.forEach(change => {
            const value = change.value;

            // Incoming messages
            if (value.messages) {
                value.messages.forEach(msg => {
                    console.log(`Message from ${msg.from}: ${msg.text?.body}`);
                    handleMessage(msg);
                });
            }

            // Delivery status
            if (value.statuses) {
                value.statuses.forEach(status => {
                    console.log(`Message ${status.id} status: ${status.status}`);
                    handleDeliveryStatus(status);
                });
            }
        })
    );
}

Message Status & Delivery Tracking

Webhook Payload: Delivery Status

Meta sends status updates via webhook when a message is delivered, read, or fails:

{
  "object": "whatsapp_business_account",
  "entry": [{
    "changes": [{
      "value": {
        "statuses": [{
          "id": "wamid.xxx",           // Message ID from your send response
          "status": "delivered",       // "sent" | "delivered" | "read" | "failed"
          "timestamp": "1675262308",
          "recipient_id": "14155551234",
          "type": "message"
        }]
      }
    }]
  }]
}

Status values:

• sent — Message reached Meta servers
• delivered — Message delivered to user's device
• read — User opened the message
• failed — Delivery failed (permanent)

Tracking Message Delivery

// When you send, store the message ID
const sendResult = await sendMessage(phone, text);
const messageId = sendResult.messages[0].id;

// Log it for webhook tracking
db.messages.insert({
    message_id: messageId,
    recipient: phone,
    sent_at: Date.now(),
    status: 'sent',
    body: text
});

// When webhook arrives with status update, match by message_id
function handleDeliveryStatus(statusUpdate) {
    const { id, status, recipient_id } = statusUpdate;

    // Update your database
    db.messages.updateOne(
        { message_id: id },
        { status: status, updated_at: Date.now() }
    );

    // Handle delivery failures
    if (status === 'failed') {
        logger.error(`Message ${id} failed to deliver to ${recipient_id}`);
        // Retry logic here
    }
}

WABA Quality Rating & Account Health

What is Quality Rating?

Your WhatsApp Business Account (WABA) has a quality rating that affects your sending ability:

How to Check Quality Rating

curl "https://graph.facebook.com/v21.0/PHONE_NUMBER_ID?fields=quality_rating" \
  -H "Authorization: Bearer YOUR_TOKEN"

# Response: { "quality_rating": "GREEN" }

What Causes Quality Rating to Drop?

• High bounce rate — sending to invalid/inactive numbers
• Spam reports — users marking your messages as spam
• High failure rate — messages consistently failing to deliver
• User blocks — users blocking your number after messages
• Policy violations — sending prohibited content

How to Improve Quality Rating

1. Validate phone numbers before sending — use the WhatsApp contacts check (error 131026)
2. Only message opted-in users — don't send unsolicited messages
3. Keep template content transactional — avoid marketing spam
4. Monitor quality metrics — check rating regularly via API
5. Respect user preferences — remove users who opt out
6. Don't retry failed numbers aggressively — wait before retrying same number

Group Messages

Note: WhatsApp Business API does NOT support group messaging directly. You can only send to individual recipients (1:1 conversations).

If you need group functionality:

• Users must add your business number to a group manually
• Messages sent to the group are treated as individual 1:1 messages
• You cannot initiate group conversations programmatically

API Versioning Strategy

All examples use v21.0 (current as of February 2026). Meta deprecates API versions annually.

Checking Your Current Version

# List all available versions
curl "https://graph.facebook.com/versions" \
  -H "Authorization: Bearer YOUR_TOKEN"

# Current version recommendations
# - v21.0 (current, recommended)
# - v20.0 (previous, will deprecate in 6 months)

Version Update Strategy

// Store version in config, not hardcoded
const API_VERSION = process.env.WHATSAPP_API_VERSION || 'v21.0';

const url = `https://graph.facebook.com/${API_VERSION}/${PHONE_NUMBER_ID}/messages`;

// When Meta deprecates a version, update .env:
// WHATSAPP_API_VERSION=v22.0

What Changes Between Versions?

• New message types or features added
• Deprecated fields removed
• Error codes may change slightly
• Response payload structure may change

Always test before upgrading — make requests against the new version in your dev environment first.

Message Constraints & Limits

Text Message Limits

Interactive Message Limits

Media URL Requirements

• Must be HTTPS only (http:// rejected)
• Must be publicly accessible (no authentication required)
• Must NOT use shorteners (bit.ly, tinyurl rejected)
• Must have correct Content-Type header
• Max file sizes:
  • Image: 16 MB
  • Audio: 16 MB
  • Video: 16 MB
  • Document: 100 MB

Rate Limits (Per WABA)

Template Approval Process

Template Submission Workflow

Create template in Meta Business Manager
        ↓
Submit for review (human review by Meta)
        ↓
Status: PENDING (24-72 hours typical)
        ↓
Status: APPROVED (can now use in messages)
    OR
Status: REJECTED (reason provided in dashboard)

How Long Does Approval Take?

• Typical: 24-72 hours
• Peak times (weekends, holidays): up to 7 days
• Fast-track: Available for high-volume WABAs (request in Meta Support)

Common Approval Issues

Check rejection reason in Meta Business Manager → Business Support → Rejected Template Messages.

Common Setup Mistakes

1. Phone Number Already on Personal WhatsApp

Symptom: Registration fails with error 133010, status stays PENDING

Cause: Phone number is already active on a personal WhatsApp account

Fix:

1. Remove phone from personal WhatsApp (go to Settings → Devices → Remove phone)
2. Wait 24 hours
3. Re-run registration API call

2. Mixing Phone Number ID with WABA ID

Symptom: API returns "Invalid parameters" for phone operations

How to tell them apart:

PHONE_NUMBER_ID: 120######## (11-12 digits, starts with 120)
WABA_ID: ######### (9-10 digits, higher number)

# Correct endpoint
POST /v21.0/PHONE_NUMBER_ID/messages  ✅

# Wrong endpoint
POST /v21.0/WABA_ID/messages  ❌

3. Token Validation Passes but Scopes Missing

Symptom: Token debug shows valid, but messaging fails with error 3/10

# Token is "valid" but missing scopes
curl "https://graph.facebook.com/debug_token?input_token=TOKEN&access_token=TOKEN"
# Response: { "is_valid": true, "scopes": ["manage_pages"] }  ← NO whatsapp_business_messaging

# Fix: Regenerate System User token with correct permissions

4. Webhook Returns JSON Instead of Raw Challenge

Symptom: Webhook verification fails silently in Meta dashboard

Wrong:

return res.json({ challenge });  // ❌ returns JSON

Correct:

return res.status(200).send(challenge);  // ✅ returns raw string

5. WABA Not Subscribed to App

Symptom: Webhooks never arrive (silent failure since 2025 Meta UI change)

Fix:

curl -X POST \
  "https://graph.facebook.com/v21.0/WABA_ID/subscribed_apps" \
  -H "Authorization: Bearer YOUR_SYSTEM_USER_TOKEN"

6. Sending Template Too Early in Approval Process

Symptom: Error 132001 "Template Unavailable"

Cause: Template still in PENDING status, not yet APPROVED

Fix: Check status in Meta Business Manager → Message Templates → wait for APPROVED status

7. Phone Number Not in WABA

Symptom: Error 131009 when trying to send

How to verify:

# Check which phone numbers are in your WABA
curl "https://graph.facebook.com/v21.0/WABA_ID/phone_numbers?fields=id,display_phone_number" \
  -H "Authorization: Bearer YOUR_TOKEN"

8. Sending Free-Form Text as First Message

Symptom: API returns 200, message ID issued, but user never receives it

Root cause: Only templates allowed as first message to any number

Fix: Always use a template for first contact

Phone Number Status Reference

Check the status field via API. Each status blocks different operations:

Error Code Reference

Fix: Token Problems (Error 190, 3, 10)

Diagnose first:

curl "https://graph.facebook.com/debug_token?input_token=YOUR_TOKEN&access_token=YOUR_APP_ID|YOUR_APP_SECRET"

Check is_valid, expires_at (0 = never expires), and scopes in the response.

Fix — create a non-expiring System User token:

1. Meta Business Manager → Settings → System Users
2. Create Admin system user
3. Add whatsapp_business_messaging + whatsapp_business_management permissions
4. Generate token — never set an expiry

Fix: Phone Number Not Registered (Error 133010)

Step 1 — check phone number status:

curl "https://graph.facebook.com/v21.0/PHONE_NUMBER_ID?fields=verified_name,code_verification_status,quality_rating,status" \
  -H "Authorization: Bearer YOUR_TOKEN"

If status is PENDING, the number is waiting for verification. Continue below.

Step 2 — set up Two-Step Verification (choose ONE method):

Option A: Manual setup (easy)

1. Meta Business Manager → WhatsApp Settings → Phone Numbers → Your Number
2. Click "Two-Step Verification" → set a PIN

Option B: API setup (easier for automation)

# Set 2FA PIN via API
curl -X POST \
  "https://graph.facebook.com/v21.0/PHONE_NUMBER_ID/two_step_verification" \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"pin": "123456"}'  # any 6-digit PIN you choose

Step 3 — register the number with the PIN:

curl -X POST \
  "https://graph.facebook.com/v21.0/PHONE_NUMBER_ID/register" \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"messaging_product": "whatsapp", "pin": "123456"}'  # same PIN from step 2

Step 4 — wait 5 minutes, then verify registration:

curl "https://graph.facebook.com/v21.0/PHONE_NUMBER_ID?fields=verified_name,code_verification_status,quality_rating,status" \
  -H "Authorization: Bearer YOUR_TOKEN"

Look for status: REGISTERED and code_verification_status: VERIFIED.

Fix: Webhook Not Verifying

Diagnose in this order:

1. Not returning raw challenge — endpoint must return the hub.challenge string value only, not JSON
2. Token mismatch — hub.verify_token Meta sends must match exactly what you set in the dashboard (case-sensitive)
3. SSL issue — Meta requires a valid cert from a trusted CA; self-signed certs are rejected
4. Timeout — your server must respond within 10 seconds
5. WABA not subscribed to App — common silent failure since 2025 Meta UI change:

# Subscribe your WABA to your App (run once)
curl -X POST \
  "https://graph.facebook.com/v21.0/WABA_ID/subscribed_apps" \
  -H "Authorization: Bearer YOUR_SYSTEM_USER_TOKEN"

# Verify the subscription exists
curl "https://graph.facebook.com/v21.0/WABA_ID/subscribed_apps" \
  -H "Authorization: Bearer YOUR_SYSTEM_USER_TOKEN"

Local development — expose localhost with a tunnel:

# Using ngrok
ngrok http 3000
# Use the https:// URL ngrok provides as your webhook callback URL in Meta

Fix: Rate Limiting (Error 130429)

Default limit is 80 messages per second. Fix with a queue and exponential backoff:

// npm install limiter
const { RateLimiter } = require('limiter');
const limiter = new RateLimiter({ tokensPerInterval: 70, interval: 'second' });

async function sendWithRetry(phone, message, attempt = 0) {
    await limiter.removeTokens(1);
    try {
        return await sendMessage(phone, message);
    } catch (err) {
        const code = err.response?.data?.error?.code;
        if (code === 130429 && attempt < 5) {
            const delay = Math.pow(2, attempt) * 1000; // 1s, 2s, 4s, 8s, 16s
            await new Promise(r => setTimeout(r, delay));
            return sendWithRetry(phone, message, attempt + 1);
        }
        throw err;
    }
}

To increase throughput beyond 80 MPS, apply in Meta Business Manager → WhatsApp → Phone Numbers → Request Increased Messaging Limit.

Fix: 24-Hour Window (Error 131047)

You cannot send free-form text to a user more than 24 hours after their last message. You must use a template.

// Instead of free-form text, send an approved template
await sendTemplate(phoneNumber, 'order_update', 'en_US', [
    { type: 'text', text: 'John' },
    { type: 'text', text: '#4521' }
]);

Create and submit templates at: Meta Business Manager → WhatsApp → Message Templates.

Fix: Template Rejected (Error 132001 or rejection in WhatsApp Manager)

Where to find rejection reason: Meta Business Manager → Business Support Home → Your WhatsApp Account → Rejected Template Messages → view policy issue.

Fix: Message Undeliverable (Error 131026)

Run this to check if a number has WhatsApp before sending:

curl "https://graph.facebook.com/v21.0/PHONE_NUMBER_ID/contacts" \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -X POST \
  -d '{"messaging_product": "whatsapp", "contacts": ["+14155551234"]}'
# Response includes "wa_id" if the number has WhatsApp, empty if not

Diagnose: "My message sends but the user never receives it" (first-contact trap)

This is the most common silent failure. The API returns success (messages[0].id) but the user receives nothing.

Root cause: You sent a free-form text message as the first outreach. Meta silently drops it.

How to tell: Check the message status webhook — the message will show failed with error 131047 or show sent but never delivered.

Rule: The very first message your app sends to any number must be a template. No exceptions.

❌ Wrong — app sends free-form text first:
   POST /messages → type: "text", body: "Hello John, your order is ready"
   → API may return 200 but message is silently dropped or returns 131047

✅ Correct — app sends template first:
   POST /messages → type: "template", name: "order_ready"
   → User receives the message and can reply
   → After user replies, free-form text is allowed for 24h

Fix: Create and approve a template for every type of first-contact message you need to send. Submit templates at Meta Business Manager → WhatsApp → Message Templates.

Practical Patterns from Production

Phone Number Validation Before Sending

Always validate phone number format and WhatsApp registration before sending:

def is_valid_phone_format(phone_digits: str) -> bool:
    """
    E.164 format validation:
      - 7-15 digits (not including +)
      - Not all same digit (e.g., 0000000 is invalid)
    """
    if not phone_digits or len(phone_digits) < 7 or len(phone_digits) > 15:
        return False
    if len(set(phone_digits)) == 1:  # all same digit
        return False
    return True

def is_registered_on_whatsapp(phone_digits: str, token: str, phone_id: str) -> bool:
    """
    Check if number is a registered WhatsApp user.
    Returns False only on definitive error 131026 (not on WhatsApp).
    Returns True if successful, uncertain (auth error, etc.), or timeout.
    """
    headers = {
        "Authorization": f"Bearer {token}",
        "Content-Type": "application/json"
    }
    data = {
        "messaging_product": "whatsapp",
        "to": phone_digits,
        "type": "text",
        "text": {"body": "_"}  # minimal text to check
    }
    try:
        r = requests.post(
            f"https://graph.facebook.com/v21.0/{phone_id}/messages",
            headers=headers,
            json=data,
            timeout=10
        )
        if r.status_code == 200:
            return True  # number is valid

        error_code = r.json().get("error", {}).get("code")
        if error_code == 131026:
            return False  # NOT on WhatsApp

        return True  # other errors — don't block
    except:
        return True  # network error — don't block

Structured Error Response Handling

def extract_error_code(response_json: dict) -> int:
    """Extract error code from Meta API response."""
    return (
        response_json.get("error", {}).get("code")
        or response_json.get("error", {}).get("error_subcode")
    )

def send_with_error_handling(phone_id: str, recipient: str, message_body: str, token: str):
    """Send message and extract detailed error info."""
    url = f"https://graph.facebook.com/v21.0/{phone_id}/messages"
    headers = {
        "Authorization": f"Bearer {token}",
        "Content-Type": "application/json"
    }
    data = {
        "messaging_product": "whatsapp",
        "to": recipient,
        "type": "text",
        "text": {"body": message_body}
    }

    try:
        r = requests.post(url, headers=headers, json=data)
        r.raise_for_status()
        return {"success": True, "message_id": r.json().get("messages")[0].get("id")}
    except requests.HTTPError as e:
        error_code = extract_error_code(e.response.json())
        error_msg = e.response.json().get("error", {}).get("message")
        return {
            "success": False,
            "error_code": error_code,
            "error_message": error_msg,
            "response_text": e.response.text
        }

Interactive Messages (Smart Buttons vs List)

def send_interactive_message(phone_id: str, recipient: str, text: str, options: list, token: str):
    """
    Intelligently sends:
      - Buttons (up to 3 options)
      - List Menu (4-10 options)

    Each option: {"id": "unique_id", "title": "Text (max 20 chars)"}
    """
    url = f"https://graph.facebook.com/v21.0/{phone_id}/messages"
    headers = {
        "Authorization": f"Bearer {token}",
        "Content-Type": "application/json"
    }

    if len(options) <= 3:
        # Send as buttons
        button_data = {
            "messaging_product": "whatsapp",
            "to": recipient,
            "type": "interactive",
            "interactive": {
                "type": "button",
                "body": {"text": text},
                "action": {
                    "buttons": [
                        {
                            "type": "reply",
                            "reply": {"id": opt["id"], "title": opt["title"][:20]}
                        }
                        for opt in options
                    ]
                }
            }
        }
        return requests.post(url, headers=headers, json=button_data)
    else:
        # Send as list menu
        list_data = {
            "messaging_product": "whatsapp",
            "to": recipient,
            "type": "interactive",
            "interactive": {
                "type": "list",
                "body": {"text": text},
                "action": {
                    "button": "See options",
                    "sections": [{
                        "title": "Available options",
                        "rows": [
                            {
                                "id": opt["id"],
                                "title": opt["title"][:24]
                            }
                            for opt in options
                        ]
                    }]
                }
            }
        }
        return requests.post(url, headers=headers, json=list_data)

Testing & Debugging Helper Scripts

Token & Phone Verification Script:

# Check if token is valid and phone number is accessible
import requests, os
from dotenv import load_dotenv
load_dotenv()

TOKEN = os.getenv('WHATSAPP_TOKEN')
PHONE_ID = os.getenv('PHONE_NUMBER_ID')

# Debug token
r = requests.get(f"https://graph.facebook.com/debug_token?input_token={TOKEN}&access_token={TOKEN}")
data = r.json()
if 'error' in data:
    print(f"❌ Token Error: {data['error']['message']}")
else:
    print(f"✅ Token Valid")
    print(f"   Expires: {data['data'].get('expires_at')} (0=never)")
    print(f"   Scopes: {data['data'].get('scopes')}")

# Check phone number
r = requests.get(
    f"https://graph.facebook.com/v21.0/{PHONE_ID}",
    headers={"Authorization": f"Bearer {TOKEN}"}
)
if r.status_code == 200:
    print(f"✅ Phone Number Accessible")
    print(f"   Display: {r.json().get('display_phone_number')}")
    print(f"   Quality Rating: {r.json().get('quality_rating')}")
else:
    print(f"❌ Phone Error: {r.json().get('error', {}).get('message')}")

Quick Debug Checklist

When a message fails, check in this order:

1. Token valid? — curl "https://graph.facebook.com/debug_token?input_token=TOKEN&access_token=APP_ID|APP_SECRET"
2. Phone number format? — E.164, no +, no spaces: "14155551234"
3. Number registered in WABA? — check WhatsApp Manager → Phone Numbers
4. Number registered with Cloud API? — run registration call if error 133010
5. 24h window? — if > 24h since last user reply, send a template instead
6. Template approved? — WhatsApp Manager → Message Templates → check status and rejection reason
7. Webhook subscribed? — verify WABA → App subscription via GET /WABA_ID/subscribed_apps
8. Rate limited? — check Quality Rating in WhatsApp Manager; implement backoff + queue