Promotional SMS vs Transactional SMS: Key Differences in India
Promotional vs transactional SMS in India explained — purpose, DND rules, sending hours, sender IDs, DLT templates and which one your business should use.
Bulk SMS India Team Updated 2 June 2025 4 min read 
"Should this be promotional or transactional?" is the most common question new SMS users ask, and getting it wrong is the most common reason messages fail. In India, the two message types follow different rules for content, timing, sender IDs and DND numbers.
This guide sets out the differences clearly so you choose the right route every time.
Updated June 2025: TRAI's 2025 amendments added message-type suffixes to sender IDs and retired the Service Explicit category. This article reflects the current rules.
What is promotional SMS?
Promotional SMS is any message meant to sell or market something: offers, discounts, new launches, event invitations or "visit our store" messages.
Key rules for promotional SMS in India:
- Delivered only between 10 AM and 9 PM.
- Not delivered to numbers registered on DND for that category, unless the customer has given digital consent.
- Sent from a numeric sender ID.
- Shows the -P suffix on the sender ID, for example AX-123456-P.
- Should give customers a way to opt out.
What is transactional SMS?
Transactional SMS carries information a customer needs because of something they did: an OTP for a login, a debit alert, an order confirmation or a booking reference.
Key rules for transactional SMS:
- Can be sent 24x7.
- Reaches DND numbers too.
- Sent from a 6-character alphabetic sender ID that represents your brand, for example BSMSIN.
- Shows the -T suffix, for example VM-BSMSIN-T.
- Must contain no promotional content at all.
And service messages?
Between the two sits service (implicit) SMS: updates to existing customers about a product or service they already use, such as delivery status, appointment reminders or renewal notices. Service messages also use a brand sender ID, can reach DND numbers and show the -S suffix. Like transactional messages, they cannot include offers.
The old Service Explicit category, used for consent-based service messages, was discontinued in May 2025. Those templates were moved to the promotional category, so DND and time-window rules now apply to them.
What your customer sees
- DLT-approved sender ID and template
- Submitted to operators in real time
- Live delivery report for every number
- Works on every mobile phone
Promotional vs transactional SMS at a glance
| Promotional | Transactional | |
|---|---|---|
| Purpose | Marketing and offers | Alerts, OTPs, confirmations |
| Sending hours | 10 AM – 9 PM | 24x7 |
| DND numbers | Blocked unless consent given | Delivered |
| Sender ID | Numeric | 6-letter brand name |
| Header suffix | -P | -T |
| Content | Can include offers | No promotional content |
| Typical users | Retail, real estate, education | Banks, apps, e-commerce |
Why the difference matters
Operators check every message against your registered DLT template. If a transactional template contains even a small promotional line, such as "Use code SAVE10 on your next order", it can be rejected. If you send a promotional message on a transactional route, it fails DLT scrubbing and you lose the credit.
Using the right category protects your sender reputation and keeps your OTPs and alerts flowing even during busy sale seasons.
Which one should your business use?
Most businesses need both:
- Transactional SMS for OTPs, payment confirmations and account alerts. See our transactional SMS service.
- Service SMS for order updates, reminders and renewal notices.
- Promotional SMS for sales, launches and loyalty campaigns. See our promotional SMS service.
A simple test: if the customer would be upset not to get the message, it is transactional or service. If the message exists to make a sale, it is promotional.
Pricing differences
Transactional and OTP routes usually cost a little more than promotional routes because they are prioritised and work around the clock. You can compare current rates for both on our bulk SMS pricing table.
Frequently asked questions
Can I send an OTP as a promotional SMS?
No. OTPs must be sent as transactional messages from a registered brand sender ID, using an approved transactional template.
Can I add an offer to an order confirmation SMS?
Not on a transactional or service template. Send the offer as a separate promotional SMS during allowed hours.
Why did my sender ID change to show -P, -T or -S?
Since May 2025, operators add a suffix to every commercial sender ID to show the message type, so customers can tell promotions from alerts at a glance. Nothing changes in your template or content.
Ready to get started?
Talk to our team about bulk SMS service — setup help, DLT guidance and test credits.
Messaging specialists with 10+ years of experience (since 2016) helping 15,000+ Indian businesses with bulk SMS, WhatsApp, RCS and voice communication.
