WhatsApp Business API for session reply — availability inquiry

Use case overview

This scenario sends a free-text WhatsApp message with sendMessage inside the 24-hour customer service window after the client asks if an item is available.

Template example

Hello, {{1}}! «{{2}}» is currently {{3}}. Reply here if you want to reserve, get a restock alert, or see similar options.

sendMessage works only when the 24-hour session window is open.

Variables and purpose

• {{1}} — client name
• {{2}} — product or service name
• {{3}} — availability status or expected date

Filled-in example

Hello, Alexey! «Premium Plan license» is currently in stock — ready to ship today. Reply here if you want to reserve, get a restock alert, or see similar options.

When to use it

• sales inventory

Business value

• Client availability question arrives via webhook inside the 24-hour session
• Inventory or booking service resolves stock or slot status for the SKU
• Session text message confirms availability or expected restock date
• Client can reserve, order, or ask alternatives in the same thread
• Lead or order pipeline updates from the automated availability response

Workflow

1. An inbound client message with an availability question arrives via webhook.
2. Your backend resolves the SKU and current stock or slot status.
3. A session text message sends the product name and availability summary.
4. The client continues the dialog to reserve or choose alternatives.
5. Delivery progress is reported asynchronously — typically sent, then delivered (or failed/undelivered).
6. Your system receives status via webhook (hooks[]) or polls delivery status and handles failures if needed.

Technical implementation

Prerequisites

• An open WhatsApp session window (client wrote first or replied within 24 hours).
• 1MSG channel with sendMessage access and inventory or booking data in your backend.

Code examples

#!/usr/bin/env node

// === Configuration (replace "___" placeholders) ===
const API_BASE_URL = "https://api.1msg.io"; // production 1MSG API base URL
const CHANNEL_ID = "___";                   // channel ID from 1MSG dashboard
const API_TOKEN = "___";                    // channel JWT token (Bearer)



// === Test data ===
const TEST_PHONE = "___";            // client phone in international format · requires open 24-hour session window
const TEST_CUSTOMERNAME = "___";    // {{1}} customer name
const TEST_PRODUCTORSERVICENAME = "___";    // {{2}} product or service name
const TEST_STATUS = "___";    // {{3}} status label

function normalizePhone(phone) {
  return String(phone).replace(/\D/g, "");
}

function assertConfigured(values) {
  for (const [key, value] of Object.entries(values)) {
    if (value === "___" || value === "" || value === undefined || value === null) {
      throw new Error(`Missing configuration value: ${key}`);
    }
  }
}

async function sendSessionTextMessage({ phone, customerName, productOrServiceName, status }) {
  assertConfigured({
    CHANNEL_ID,
    API_TOKEN,
    phone,
    customerName,
    productOrServiceName,
    status,
  });

  const url = `${API_BASE_URL}/${CHANNEL_ID}/sendMessage`;
  const requestBody = {
    phone: normalizePhone(phone),
    body: `Hello, ${customerName}! «${productOrServiceName}» is currently ${status}. Reply here if you want to reserve, get a restock alert, or see similar options.`,
  };

  const res = await fetch(url, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      Authorization: `Bearer ${API_TOKEN}`,
    },
    body: JSON.stringify(requestBody),
  });

  const raw = await res.text();
  let data;
  try {
    data = JSON.parse(raw);
  } catch {
    data = null;
  }

  if (!res.ok || !data || data.sent !== true) {
    console.error("Send failed. API response:");
    console.error(raw);
    process.exit(1);
  }

  console.log("Message sent to client.");
  console.log("API response:", raw);
  return data;
}

if (require.main === module) {
  sendSessionTextMessage({
    phone: TEST_PHONE,
    customerName: TEST_CUSTOMERNAME,
    productOrServiceName: TEST_PRODUCTORSERVICENAME,
    status: TEST_STATUS,
  }).catch((err) => {
    console.error("Execution failed:", err.message);
    process.exit(1);
  });
}

module.exports = { sendSessionTextMessage };

Immediate API response (synchronous)

• HTTP 2xx and JSON "sent": true mean 1MSG accepted the message for sending — not that it already reached the customer's phone.
• Save the `id` field from the response (value looks like wamid.…). Use it to correlate delivery callbacks or polling.
• The response may also include message and description — informational only.

Delivery status (asynchronous)

• Register a webhook (POST …/webhook) so 1MSG POSTs delivery updates to your HTTPS endpoint in a separate `hooks[]` payload (sent, delivered, read, or failed/undelivered when applicable).
• Optionally poll: GET {base}/{channel}/hookInfo?messageId=<id from sendTemplate>.
• In practice, delivery often completes within a few seconds — but that is not guaranteed by the API contract.

Common errors

• Session window closed (no client message within 24 hours)
• Invalid or non-normalized phone number
• Missing or invalid message body / media URL
• Delivery failure — check status webhook and retry policy

FAQ

• Do I need a template? No — this scenario uses a session message inside the 24-hour customer service window.
• When does the session window close? If the client has not written or replied within 24 hours, sendMessage will fail until a template reopens the chat.
• How do I check delivery? sent: true only confirms acceptance. Track delivery via webhook hooks[] or polling.
• What if the message is not delivered? Log the failed/undelivered hook, verify the session window, then retry or use a template.
• Can I connect this to my CRM or backend? Yes — trigger the API call from your inbound webhook or workflow engine.

Related

• Knowledge base
• Creating a template
• Sending a template
• SDK