WhatsApp Business API for failed delivery attempt notification

Use case overview

The scenario sends the customer a personalized WhatsApp template when a delivery attempt fails. The message includes the customer name, order number, product name, and instructions for the next attempt or pickup. A static URL button opens reschedule or tracking.

Template example

Hello, {{1}}! The courier could not deliver order #{{2}} for "{{3}}". {{4}}.

[Reschedule delivery]

The reschedule or tracking URL button is fixed in the Meta template — only body variables are sent via the API.

Variables and purpose

• {{1}} — customer name
• {{2}} — order number
• {{3}} — product name
• {{4}} — next attempt date, pickup option, or failure reason

Filled-in example

Hello, Alexey! The courier could not deliver order #10482 for "Wireless headphones". Redelivery scheduled for tomorrow between 10:00 AM and 2:00 PM. Choose a convenient time using the link below..

[Reschedule delivery]

When to use it

• last-mile logistics
• e-commerce
• integrators

Business value

• Carrier or TMS emits a failed-attempt event
• System resolves the customer phone number and attempt details
• Template message is built with four body variables and a static URL button
• Customer receives WhatsApp notice with clear redelivery options
• Delivery status is logged for CRM or logistics follow-up

Workflow

1. The carrier records a failed delivery attempt and fires an event.
2. The system resolves the customer phone number and attempt fields.
3. A personalized template message is built with four body variables and a static URL button.
4. The customer receives the WhatsApp update and can reschedule via the button.
5. Delivery result is logged; errors are handled according to platform rules.
6. Delivery progress is reported asynchronously — typically sent, then delivered (or failed/undelivered).
7. Your system receives status via webhook (hooks[]) or polls GET …/hookInfo?messageId=<id> and handles failures if needed.

Technical implementation

Prerequisites

• A 1MSG account with WhatsApp Business API connected and an approved message template.
• Customer phone number in international format (without + and spaces).
• Attempt data: customer name, order number, product name, next-step note.

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)

const TEMPLATE_NAME = "___";                // approved template name
const TEMPLATE_NAMESPACE = "___";           // template namespace (422 without it)
const TEMPLATE_LANGUAGE = "___";            // template language code, e.g. "en"



// === Test data ===
const TEST_PHONE = "___";            // client phone in international format
const TEST_CUSTOMERNAME = "___";    // {{1}} customer name
const TEST_TICKETNUMBER = "___";    // {{2}} ticket number
const TEST_PRODUCTNAME = "___";    // {{3}} product name
const TEST_NEXTSTEP = "___";    // {{4}} next step

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 sendTemplateMessage({ phone, customerName, ticketNumber, productName, nextStep }) {
  assertConfigured({
    CHANNEL_ID,
    API_TOKEN,
    TEMPLATE_NAME,
    TEMPLATE_NAMESPACE,
    TEMPLATE_LANGUAGE,
    phone,
    customerName,
    ticketNumber,
    productName,
    nextStep,
  });

  const url = `${API_BASE_URL}/${CHANNEL_ID}/sendTemplate`;

  // params carries body ONLY. Button text is fixed in the Meta template — no button param.
  const requestBody = {
    phone: normalizePhone(phone),
    template: TEMPLATE_NAME,
    namespace: TEMPLATE_NAMESPACE,
    language: {
      policy: "deterministic",
      code: TEMPLATE_LANGUAGE,
    },
    params: [
      {
        type: "body",
        parameters: [
          { type: "text", text: String(customerName) }, // {{1}} customer name
          { type: "text", text: String(ticketNumber) }, // {{2}} ticket number
          { type: "text", text: String(productName) }, // {{3}} product name
          { type: "text", text: String(nextStep) }, // {{4}} next step
        ],
      },
    ],
  };

  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) {
  sendTemplateMessage({
    phone: TEST_PHONE,
    customerName: TEST_CUSTOMERNAME,
    ticketNumber: TEST_TICKETNUMBER,
    productName: TEST_PRODUCTNAME,
    nextStep: TEST_NEXTSTEP,
  }).catch((err) => {
    console.error("Execution failed:", err.message);
    process.exit(1);
  });
}

module.exports = { sendTemplateMessage };

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

• Invalid or non-normalized phone number
• Unapproved or missing template name / namespace
• No customer opt-in for WhatsApp business messages
• Template variable count mismatch (422 from API)
• Delivery failure — check status webhook and retry policy

FAQ

• Do I need an approved template? Yes — cold-start WhatsApp messages require a Meta-approved template.
• Can I customize the message text? Body variables are dynamic; fixed text and button labels are set in the Meta template.
• How do I check delivery? sent: true only confirms acceptance. Track delivery via webhook hooks[] or GET …/hookInfo?messageId=<id>.
• What if the message is not delivered? Log the failed/undelivered hook, verify opt-in and template status, then retry or fall back to another channel.
• Can I connect this to my CRM or backend? Yes — trigger the API call from your platform webhook or event handler.

Related

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