SMS is the one channel every customer can receive. No app, no data plan, no smartphone required. That is why, even with WhatsApp and RCS growing fast, Bulk SMS remains the backbone of business communication in India: OTPs, order updates, payment alerts and reminders still travel over SMS first.

This guide explains how business SMS actually works, what the rules are, and how to use it well.

What is Bulk SMS?

Bulk SMS means sending text messages from a business system to many customers at once through a messaging platform, rather than from an individual handset. The platform connects to telecom operators, handles routing and retries, and returns a delivery status for every message.

Two things make it "business" SMS rather than ordinary texting:

• A registered Sender ID (a six-character header such as MTRXTL) so customers recognise who is messaging them.
• Pre-approved templates, required in India under the DLT framework, so each message matches a format the regulator has seen.

Transactional vs promotional: why the route matters

Every business message falls into one of two categories, and they travel on different routes.

Transactional (and service) SMS

Information the customer expects because of something they did: an OTP, an order confirmation, a delivery update, a bank alert, an appointment reminder. These can be sent 24×7, including to numbers on the Do Not Disturb (DND) list, and they get priority routing.

Promotional SMS

Offers, launches and marketing content. These go only to customers who have opted in, only between 10 AM and 9 PM, and never to DND numbers. Promotional traffic uses a separate header so a delayed campaign never slows down an OTP.

If a business mixes the two, promotional messages get blocked and transactional ones get delayed. Keeping the routes separate is the single most important operational decision.

DLT: the rulebook for SMS in India

Since 2020, business SMS in India runs on Distributed Ledger Technology (DLT) platforms operated by the telecom operators. Before you send anything you need:

1. Entity registration – your company, verified with PAN/GST documents.
2. Header (Sender ID) registration – separate headers for transactional and promotional use.
3. Template registration – the exact text of each message, with variables marked as {#var#}.
4. Consent – for promotional messages, a record that the customer agreed.

We handle this setup with you as part of onboarding; see Bulk SMS for what is included.

What good Bulk SMS looks like

• Short and specific. One message, one purpose. "Your order #48213 has shipped. Track: mtx.link/t/48213" beats three sentences of marketing.
• Sent at the right moment. Transactional messages go out the instant the event happens. Promotional messages go out when your customers are actually free.
• Personalised with data you already have. Name, order number, appointment time, amount due.
• Measured. Every message returns a delivery status. Failed numbers should be cleaned from your list, not retried forever.
• Paired with a reply path. Where customers may want to respond, consider the WhatsApp Business API as the primary channel with SMS as the fallback.

Common use cases

Use case	Route	Example
OTP & login	Transactional	"482913 is your Mantraxtel verification code. Valid for 5 minutes."
Order updates	Transactional	"Your order is out for delivery today between 2–4 PM."
Payment reminders	Service	"Your invoice INV-2201 of ₹12,400 is due on 20 Sep."
Offers	Promotional	"Weekend sale: 20% off on all plans. Opt out: reply STOP."

Getting started

Tell us your use case and expected volume. We will set up your entity, headers and templates on DLT, connect the right routes and give you delivery reporting from day one. Talk to an expert to begin.