SMS Notifications

Why First — The Scenario

Picture this: a parent pays their child's tuition fee through your app at 9 PM. The payment goes through, the fee record updates to "paid", and a receipt is generated automatically. But the parent hears nothing. No confirmation. No message. They refresh the app twice, check their email, and then call the school to ask if the payment actually went through.

That one phone call costs the school staff time, erodes trust, and leaves the parent anxious.

SMS fixes this in 3 seconds. The moment the payment confirms, a message lands on the parent's phone:

Fee payment confirmed! ₹12,500 received for Priya Sharma (Class 7B). Receipt ID: EDU12345. Thank you.

No app open required. No internet connection required. It just works.

This is why every serious Indian consumer app — banks, e-commerce, food delivery, healthcare — uses SMS for critical notifications.

---

The Excel Analogy

You already know mail merge in Excel or Word. You have a list of 500 client names and addresses, a template letter, and Word fills in each person's name and sends a personalised letter to every client.

SMS APIs work exactly like that — but automated and instant.

The difference: mail merge is something you trigger manually once. An SMS API fires automatically, every time a user does something in your app, 24 hours a day, without you touching anything.

---

The Two Types of SMS in India

India's telecom regulator (TRAI) divides all commercial SMS into two categories. This matters because you need different approvals for each.

For building apps, you will almost always use Transactional SMS. Promotional SMS is a marketing function — relevant later, not during development.

---

Why Indian Apps Need DLT Registration

Since 2021, TRAI (Telecom Regulatory Authority of India) mandated that every business sending commercial SMS must register on a DLT (Distributed Ledger Technology) platform. Every message, sender ID, and template must be pre-approved.

Without DLT registration, your SMS messages will be silently blocked by carriers. They will not bounce back with an error — they simply will not arrive. Users will never know they were supposed to receive a message.

Think of it like GST registration for your CA clients. You cannot collect GST until you are registered. Similarly, you cannot send commercial SMS until your templates and sender ID are approved on DLT.

---

Why MSG91

There are several SMS providers in India — Exotel, Twilio (US-based), ValueFirst, and others. MSG91 is the standard choice for Indian startups for these reasons:

• Built specifically for the Indian market — DLT integration is built into their dashboard
• Competitive pricing (per-SMS rates, credit system)
• Good API documentation
• Supports OTP, transactional, promotional, and WhatsApp in one platform
• Used in production by thousands of Indian apps
• Supabase edge functions work cleanly with their REST API

---

What You Will Learn in This Module

---

The Big Picture Flow

Before diving into individual pages, here is the complete picture of how SMS works in your app:

Every step in this flow matters. The pages in this module walk through each one.