WhatsApp Business API for upcoming visit reminder

Use case overview

The scenario sends the client a personalised WhatsApp template before a scheduled visit. The message includes the client name, service name, visit date, and visit time. A static URL button opens booking details.

Template example

Hello, {{1}}! Reminder: your appointment for {{2}} is on {{3}} at {{4}}. We look forward to seeing you.

[View booking]

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

Variables and purpose

• {{1}} — customer name
• {{2}} — service or appointment type
• {{3}} — visit date
• {{4}} — visit time

Filled-in example

Hello, Maria! Reminder: your appointment for dental check-up is on June 15, 2026 at 2:00 PM. We look forward to seeing you.

[View booking]

When to use it

• clinics and salons
• field service
• integrators

Business value

• Scheduling system triggers a reminder before the upcoming visit
• Client phone number and booking fields are resolved
• Personalised reminder message is prepared with four body variables
• WhatsApp template message is delivered to the client
• Client can open booking details via the URL button without replying in WhatsApp
• Delivery status is logged for the scheduling system or CRM

Workflow

1. The scheduling system detects an approaching visit and fires a reminder event.
2. The system resolves the client phone number and booking fields.
3. A personalised template message is built with four body variables and a static URL button.
4. The client receives the WhatsApp reminder and can open booking details via the button.
5. Delivery result is logged for the scheduling system or CRM.
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).
• Booking data: customer name, service, date, and time.

Code examples

Node.js

#!/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_SERVICE = "___";    // {{2}} service name
const TEST_BOOKINGDATE = "___";    // {{3}} booking date
const TEST_BOOKINGTIME = "___";    // {{4}} booking time

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, service, bookingDate, bookingTime }) {
  assertConfigured({
    CHANNEL_ID,
    API_TOKEN,
    TEMPLATE_NAME,
    TEMPLATE_NAMESPACE,
    TEMPLATE_LANGUAGE,
    phone,
    customerName,
    service,
    bookingDate,
    bookingTime,
  });

  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(service) }, // {{2}} service name
          { type: "text", text: String(bookingDate) }, // {{3}} booking date
          { type: "text", text: String(bookingTime) }, // {{4}} booking time
        ],
      },
    ],
  };

  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,
    service: TEST_SERVICE,
    bookingDate: TEST_BOOKINGDATE,
    bookingTime: TEST_BOOKINGTIME,
  }).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.

CTA

Ready to use upcoming visit reminder? Connect your 1MSG channel and run the code examples above.

Related

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