Bulk SMS in India: DLT registration, headers, content templates and consent under TRAI's TCCCPR rules as amended in 2025

To send bulk SMS in India, your business has to be registered on a telecom operator's DLT platform with three things in place: your entity, your headers (the sender ID of up to eleven characters that appears on the phone), and a registered content template for every message you send. A message that does not match a registered header and template is not delivered. These rules come from TRAI's Telecom Commercial Communications Customer Preference Regulations, 2018 (TCCCPR), as amended by the Second Amendment Regulations of 12 February 2025, and they apply the same way to a shop in Thiruvananthapuram, a hospital in Pune and a bank in Mumbai.

Both regulations were read on 22 October 2026 from the Internet Archive's copies of the TRAI files, because trai.gov.in did not respond that day.

What DLT is, and who sits on it

The 2018 regulations define Distributed Ledger Technologies (DLT) as a set of technological solutions that keeps "a single, sequenced, standardized and cryptographically-secured record of activities" shared across many participants. In plain terms, every operator keeps shared registers of who may send commercial messages, under which headers, with which templates, and to whom. The regulations name a Header Register, a Content Template Register, a Consent Register and a Preference Register.

Three parties matter to a business buying bulk SMS:

• You, the sender (often called the principal entity). The regulations treat as the sender the business that owns the header or is promoting the goods or services, not only the company that pressed send.
• The telemarketer: the bulk SMS company that transmits messages for you, which must itself be registered.
• The access provider: the telecom operator whose network carries the message and which runs the DLT registers.

Because the law treats you as the sender, a bulk SMS provider cannot carry your liability for you. Register the entity and the headers in your own company's name.

The four types of message and the header suffix

The 2025 amendment rewrote the message types. It also says the type of a message should be recognisable from the header, by adding "-P", "-S", "-T" and "-G" for Promotional, Service, Transactional and Government messages.

Type	What it is under the amended rules	Consent position
Transactional (-T)	Sent to your own customer in response to a transaction the customer started, within thirty minutes, such as an OTP, a transaction alert or a refund update	Does not need explicit consent
Service (-S)	Information to your customer about a product or service they use: warranty, recall, software update, delivery, periodic balance alerts	Does not need explicit consent if it is not promotional; a service message to complete a purchase for a non-customer needs explicit consent, valid for seven days unless TRAI directs otherwise
Promotional (-P)	Any message containing promotional material or an advertisement of a product or service	Delivered only to people who have not blocked that category, or who gave consent; must carry an opt-out in the same message
Government (-G)	Messages sent on the directions of central or state government or a constitutional body	Delivered even to numbers that are fully blocked

One rule catches many marketers: under the amendment, if promotional content is mixed into a transactional or service message, the whole message is treated as promotional. An order confirmation with a discount code for next time is a promotional message.

Customer preferences and the 1909 service

Every operator must let customers record their preferences free of cost by sending an SMS to 1909, calling 1909, through IVRS, USSD, an approved app or a web portal with OTP login. Under the 2025 schedule, a customer can block only promotional messages, fully block everything except government messages and transactional or service messages sent under inferred consent, or block single categories. The categories listed are banking, insurance, financial products and credit cards; real estate; education; health; consumer goods and automobiles; communication, broadcasting, entertainment and IT; tourism and leisure; and food and beverages.

The amended definition adds one important exception. If you have collected explicit digital consent from a person as the regulations provide, your promotional messages with that consent are delivered even if the person has blocked the category. That is why consent collected properly is worth more than any purchased list.

Templates, variables and links

A content template is the registered wording of a message. The 2018 definition splits it into a fixed part, common to every recipient, and a variable part, such as a name, an amount, a date or a reference number. A promotional template is fixed content only. The 2025 amendment tightened the template rules that operators apply:

• more than three variables in a template are allowed only in special circumstances, with recorded justification, and each variable must be pre-tagged for what it will hold;
• at least thirty percent of a template's characters must be fixed content;
• one content template may not be linked with more than one header;
• templates that go unused can be temporarily deactivated and reactivated on request;
• messages containing URLs, APKs, OTT links or call-back numbers are scrubbed against whitelisted data that you upload, with an undertaking that the links are not malicious.

In practice, register every link domain and every call-back number before a campaign, or the messages that carry them will not be delivered.

Complaints, misuse and suspension

Under the amendment, a customer can complain about an unwanted commercial message within seven days of receiving it, and the operator checks that date before acting. Where headers or templates are misused, operators suspend the sender's traffic until the sender has filed a complaint with law enforcement and reviewed all its headers and templates. Senders and telemarketers must self-certify their registration details, headers and templates every year, and a failure to certify leads to automatic suspension. Headers unused for ninety days can be deactivated, and repeat violations lead to blacklisting across all operators for at least one year.

How to choose a bulk SMS provider in India

Most "bulk SMS service provider in India" searches end with a price per message. Compare these first:

• Registration in your name. The entity, headers and templates should be registered by you on an operator's DLT portal, with the provider added as your telemarketer.
• Template help. Ask how the provider drafts templates within the variable and fixed-content rules, and how quickly it handles rejections.
• Link and number whitelisting. Ask how you upload your URLs and call-back numbers and who checks them before a campaign.
• Consent records. Ask how the platform records consent and opt-outs, and whether you can export them.
• Delivery reports. Ask for reports that separate delivered, failed and blocked by preference, so you can see why a message did not arrive.
• The rest of the channel mix. SMS is one channel; our comparison of SMS marketing companies and the consent stack each one runs covers how global platforms handle consent.

Bulk SMS in India, the questions businesses ask

Do I need DLT registration to send bulk SMS?

Yes. Operators must not carry commercial messages except under headers assigned to registered senders, and each message must match a registered template. A provider that offers to send without your registration is sending under someone else's identity.

What is a header, and can I choose it?

A header is the alphanumeric string, of up to eleven characters, that identifies you as the sender. You apply for it on the DLT platform, usually close to your brand name, and the amended rules add a suffix that shows the message type.

Can I send offers to my existing customers without consent?

An offer is a promotional message, even to an existing customer. It reaches people who have not blocked that category, or anyone who gave you explicit consent. Transactional and service messages must stay free of promotional content.

Why are my messages not being delivered?

The usual causes are a message that does not match its registered template, an unregistered link or call-back number, a template linked to a different header, or a recipient who has blocked that category. Ask your provider for delivery reports that show which one applies.

Is the process different in Kerala or any other state?

No. TCCCPR is national. A business in Thiruvananthapuram registers on the same DLT platforms and follows the same template and consent rules as one in Delhi.

When the question goes to an assistant instead of Google

More buyers now ask ChatGPT or Gemini "which bulk SMS provider in India handles DLT registration properly?" and get a short list of names. The providers named are the ones the assistant has read about in its sources, and the answer can differ from one assistant to the next.

If you sell SMS services, finding out whether those answers include you is a different task from sending messages, and it belongs to a newer category of tool. AI Knows Us is one: it puts buyer questions to ChatGPT, Gemini, Perplexity, Claude and Google AI Overviews, records which providers each answer recommends, and shows the sources behind it.