India is one of the world’s largest mobile markets. DataReportal’s Digital 2025 India report counted around 1.12 billion active cellular connections at the start of 2025. Almost every customer you have can receive a text message, including people who rarely check their inbox and those on basic feature phones. That reach is why Indian banks, e-commerce platforms, clinics and coaching institutes rely on SMS for OTPs, delivery updates and reminders.
It is also why India regulates commercial SMS more tightly than most countries. Before you plan a campaign, you need to understand how TRAI’s rules shape what you can send, when, and to whom.
How commercial SMS works in India
Commercial messaging is governed by TRAI’s Telecom Commercial Communications Customer Preference Regulations, 2018 (TCCCPR), amended again in February 2025. The system is built on DLT (distributed ledger technology) platforms run by the telecom operators. Four things must be registered there before a message can be delivered:
- Your business as a principal entity, with a unique entity ID.
- Your sender headers, the short sender name customers see at the top of the message.
- Your content templates, the approved wording of each message, with placeholders for variable parts such as a name or amount.
- Consent where it is needed, recorded against the relevant category.
Operators check each message against these records. A text whose header or wording does not match a registered template is blocked, even if every recipient wants it.
Promotional, service and transactional routes
| Category | Typical use | Main rule |
|---|---|---|
| Promotional | Sale announcements, new launches, offers | Filtered against DND preferences; delivered only during daytime hours |
| Service (explicit consent) | Updates the customer has specifically agreed to receive | Needs recorded consent |
| Service (inferred consent) | Messages linked to an existing relationship, such as a renewal reminder | Cannot contain promotional content |
| Transactional | OTPs and alerts triggered by the customer’s own transaction | Must be sent shortly after the transaction it relates to |
Since May 2025, operators add a suffix to sender headers so recipients can see the category at a glance: -P for promotional, -S for service, -T for transactional and -G for government. Under the 2025 amendment, any message mixing promotional content with a service or transactional message is treated as promotional, so keep your offers out of your OTPs.
DND and the National Customer Preference Register
Indian mobile users can block promotional messages entirely or by category (such as banking, real estate or education) through the National Customer Preference Register. Promotional SMS is scrubbed against these preferences automatically, so a slice of any purchased or old list will never be reached. Consent you collect yourself, through a clear opt-in on your subscription form, is the durable asset.
Using Mailpro for SMS
Mailpro lets you manage email and SMS contacts in one account, personalise messages with contact fields, schedule sends in advance and follow each campaign in SMS statistics. In Mailpro’s own customer survey, users rated SMS deliverability 9.8/10.
For Indian numbers, your DLT registration stays your responsibility as the sender. Have your entity ID, headers and template IDs ready, and check with Mailpro support how they should be applied to +91 traffic before your first campaign. The general rules and number formats are covered in SMS laws and restrictions and the country code list.
Practical tips for Indian SMS campaigns
- Store numbers in full international format: +91 followed by the ten-digit mobile number.
- Register templates in each language you use. A Hindi template in Devanagari is a different template from its English equivalent, and Unicode messages carry fewer characters per SMS.
- Time promotional texts for daytime IST. Operators block promotional delivery at night, and a mid-morning or early-evening send usually reads better anyway.
- Plan festival campaigns early. Template approval takes time, so register your Diwali, Holi or Independence Day wording weeks before the date.
- Pair SMS with email. Send the full story by email and a short SMS reminder to non-openers, as described in combining SMS and email campaigns.
Wondering whether SMS is worth the registration effort? Read are SMS campaigns effective in India?, and see the email marketing law page for how the DPDP Act applies to phone numbers too.