DLT Registration for SMS in India, Explained

If you have ever loaded an SMS pack, pushed a campaign to your customer list and watched the delivery report come back blank, you have already met DLT. Since 2020, every business sending SMS to Indian mobile numbers must register itself, its sender IDs and its message content on a Distributed Ledger Technology platform. Telecom operators check each message against this registry before delivering it, and anything unregistered is quietly dropped. This post explains the system in plain terms and lists what you actually need to do.

What DLT is and why it exists

DLT is a shared, blockchain-based registry mandated by TRAI under its commercial communication regulations to curb SMS spam. Each major operator runs a DLT portal — Airtel, Jio, Vi and BSNL all have one — but a registration completed on any one platform is honoured across operators. In practice, most businesses register on whichever platform their SMS provider recommends, because that keeps support simple.

Step one: entity registration

You first register your business as a Principal Entity. This needs your PAN, GST or other incorporation proof, a letter of authorisation and a modest one-time fee. On approval you receive a Principal Entity ID. Your SMS provider will ask for this ID before enabling anything else, so do it first — approval typically takes a few working days.

Step two: header registration

A header is your sender ID — the name recipients see, such as a six-character alphanumeric code for service and transactional messages. Promotional messages use numeric headers. Register a header people can recognise as your brand; an unfamiliar code hurts trust and response, whatever the message says.

Step three: template registration

Every distinct message must be registered word for word, with dynamic portions marked as {#var#} variables. You also declare a category:

• Transactional — OTPs and similar critical messages, narrowly defined.
• Service implicit — updates to your own customers about their orders, applications or accounts.
• Service explicit and promotional — offers and marketing, which require recorded consent.

The operator's scrubbing engine compares each outgoing message against the registered template. If your text drifts from what was registered — even by punctuation in some cases — the message is blocked. This is the single most common reason "SMS is not working".

How ASH keeps you on the right side of DLT

SMS in ASH is an Enterprise-plan capability and is built DLT-first. Each template you create in ASH stores its registered DLT template ID and variables, so what your team and your automations send always matches what the operator expects. The module is provider-agnostic: connect MSG91 or Twilio through configuration when you are ready, and until then sends run in a safe sandbox so you can test workflows without touching a live route. When the workflow builder triggers an SMS on a stage change, the same registered template goes out every time — no free-typed messages for scrubbing to reject. See plans and pricing for what the Enterprise tier includes, and the features overview for how SMS sits alongside WhatsApp and email.

DLT feels bureaucratic the first time, but it is a one-time setup: entity, headers, templates. Do it properly once, keep your templates disciplined, and SMS becomes a dependable channel instead of a mystery.