Promotional vs Transactional SMS in India
Short answer: Transactional SMS carries messages a customer expects because of something they did, such as an OTP, a payment confirmation or a delivery update. Promotional SMS carries offers and marketing. In India the two are registered under different categories on the DLT platform, use different headers, and promotional messages are subject to DND checks and permitted sending hours.
Picking the wrong category is a common reason for blocked templates. Use the table to decide which one your message belongs in, then register the right header and template. For the regulator's rules, see trai.gov.in, and our DND compliance guide.
Last updated: 2 November 2026.
How the categories differ
| Transactional | Service | Promotional | |
|---|---|---|---|
| Purpose | Triggered by a customer action; critical info such as OTPs and bank alerts | Updates about an existing service, such as order or appointment status | Offers, discounts, announcements and marketing |
| Examples | Login OTP, debit alert, payment confirmation | Order shipped, appointment reminder, policy renewal notice | Sale announcement, new product launch |
| Needs recipient consent? | Message is expected from the customer's action | The customer has an existing relationship with you | Customer consent and DND status are checked |
| DND numbers | Not blocked for genuine transactional use | Handled by category rules | Blocked for numbers that opted out |
| Sending hours | Any time | Per category rules | Restricted to TRAI's permitted window |
| Content check | Template must match exactly | Template must match exactly | Template must match exactly; promotional content on a transactional header is filtered |
How to decide which category a message is
- If the message has an offer, discount or call to buy, treat it as promotional, even if it also mentions an order.
- If it is only information about something the customer did, it is likely transactional or service.
- When in doubt, classify as promotional. Mislabelling promotional content as transactional gets templates rejected and can put your header at risk.
What to register for each
Register your entity once, then a header for each category you use, then each template. See header registration and template format and variables. For the API that sends them, see transactional SMS API and SMS API.
Mixed messages
An order confirmation that adds "50% off your next order" becomes promotional. Send the confirmation on its own as a service or transactional message, and send the offer separately as promotional to people who have not opted out.
Promotional vs transactional questions
Can I send promotional SMS from a transactional header?
No. Operators check the content, and promotional text sent on a transactional header is filtered even if the template was approved.
Do OTPs need a transactional template?
Yes. OTPs are sent as transactional messages with a registered template that contains a variable for the code.
What is the difference between service and transactional SMS?
Transactional covers time-critical messages such as OTPs and bank alerts. Service messages update customers about services they already use. Both need registered templates.
Does DND affect transactional SMS?
DND preferences apply to promotional messages. Genuine transactional and service messages are not blocked by DND.
Where do I register this?
On the DLT platform of the telecom operators, through the portal or with your provider's help.
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