How to Write SMS Templates That Comply with DLT

If you send commercial SMS to Indian numbers, the DLT framework is not optional. TRAI requires every business, sender ID and message template to be registered before a single text goes out. Get it right and your messages deliver reliably; get it wrong and they are silently blocked by the operators. Here is what DLT asks of you and how ASH keeps the pieces in order.

What DLT actually requires

DLT (Distributed Ledger Technology) is the registration system Indian telecom operators use to curb spam. There are three registrations to know: your business as a Principal Entity, one or more sender IDs (headers), and the content templates themselves. Each registered template is issued a template ID that must accompany the message when it is sent. No registration, no delivery.

Sender IDs, or headers

A sender ID — the six-character header your SMS appears from, like ASHEDU — is registered against your entity and tied to a purpose. Transactional and promotional traffic generally use different headers, and you cannot push promotional content through a transactional header. Choose headers a recipient will recognise as you, and register one per message type you genuinely need.

Transactional versus promotional

The category you register a template under decides where and when it can be sent:

• Transactional or service — one-time passwords, payment confirmations, application updates. These reach even numbers on the Do-Not-Disturb list because they are essential to a service the person is already using.
• Promotional — offers, campaigns, announcements. These are subject to DND preferences and time-of-day rules.

Registering a promotional message as transactional to dodge DND is exactly the misuse the framework is built to catch. Match the category to the true intent.

Variables and the template text

DLT templates allow variable placeholders for the parts that change — a name, an amount, an OTP — while the fixed wording stays exactly as registered. The message you send must match the approved text apart from those variables. If you rewrite the body on the fly, it will not match its template ID and the operator will drop it.

How ASH stores your DLT details

SMS is an ASH Enterprise-plan feature, and it is provider-agnostic — it runs in a mock sandbox until you connect a provider such as MSG91 or Twilio through environment settings. Because ASH treats SMS as DLT-ready, each template carries its DLT fields, including the template ID, alongside the message body. You register the content with your operator, store the matching template and its ID in ASH, and the correct identifiers travel with every send. That keeps live sends aligned with what you registered, rather than relying on memory.

A short pre-send checklist

• Entity, header and template all registered and approved.
• Category — transactional or promotional — matches the real intent.
• Message text matches the registered template, variables aside.
• Identifiers — the correct template ID and header are attached to the send.

DLT rewards businesses that keep their records tidy. Register honestly, store the IDs where your sending system can use them, and your legitimate messages get through. For the neighbouring channel, see how to write WhatsApp templates that get replies, or review plan details on the pricing page.