Bulk SMS & DLT in India: A Beginner's Guide
Updated 1 June 2026 · 6 min read
Bulk SMS reaches any phone instantly with no app or internet — which is why it's still the backbone of OTPs and critical alerts. In India it requires DLT (Distributed Ledger Technology) registration of your business entity, sender ID and message templates, or your messages get silently blocked. Many businesses use SMS and WhatsApp together: SMS for verification and essential alerts, WhatsApp for richer conversations.
Key takeaways
- SMS reaches every phone — no app, no internet, no opt-in dependency — so it's unbeatable for OTPs and alerts.
- DLT registration is mandatory in India: register your entity, sender IDs and templates or messages are blocked.
- Templates are categorised (OTP, transactional, service, promotional) and must be pre-registered.
- SMS is the reliable fallback when a WhatsApp message doesn't land.
- Most businesses use SMS + WhatsApp together rather than choosing one.
Why SMS still matters in a WhatsApp world
WhatsApp is powerful, but SMS does things WhatsApp can't. It reaches every phone with no app, no internet and no opt-in dependency, which is why it remains the backbone of OTPs and critical alerts. When a customer needs a one-time password to log in or pay, or a 'your order has shipped' message, SMS delivers it instantly and universally. It's also the reliable fallback when a WhatsApp message doesn't arrive. For many businesses the right answer isn't WhatsApp or SMS — it's both, with SMS handling verification and essential transactional traffic.
What is DLT registration, and why does it trip people up?
DLT (Distributed Ledger Technology) registration is mandated by TRAI to stop spam, and it's where most businesses get stuck. There are several moving parts: registering your business entity, getting your sender IDs (headers) approved, registering each message template, and mapping templates to the right category — transactional, OTP, service or promotional. The rules also change, including updates to categories and sender-ID formats. Without correct registration, your messages are silently filtered: no error, no delivery. Getting the entity, header and templates right is the difference between SMS that works and SMS that quietly fails.
- Register your business entity on the DLT platform
- Get sender IDs (headers) approved
- Register and categorise every message template
- Keep it current as DLT rules and formats change
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Frequently asked questions
Is SMS still worth it when I have WhatsApp?
Yes. SMS reaches any phone with no app, internet or opt-in needed, which makes it essential for OTPs and critical alerts and a reliable fallback when WhatsApp doesn't land. Many businesses use both.
What is DLT registration and do I need it?
DLT registration is mandatory in India for business SMS. Your entity, sender ID and every template must be registered, or messages are silently blocked. It's a one-time setup that's kept compliant over time.
How long does DLT registration take?
Entity and template approvals typically complete within a few business days once details are provided, then sender IDs and templates are kept current as rules change.
How much does bulk SMS cost?
There's a one-time DLT setup plus per-SMS costs that vary by type and volume. It's priced per project — get a quote for your SMS needs.
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