SMS remains the highest-attention marketing channel available to Indian businesses. Open rates sit near 98 percent, and around 90 percent of messages are read within three minutes of delivery. Compare that with typical email open rates of 20 to 25 percent and it is clear why banks, e-commerce brands, schools and local retailers keep investing in bulk SMS. Unlike app push notifications, SMS reaches feature phones and smartphones alike, with no internet connection required — a decisive advantage in tier 2 and tier 3 India.
That reach comes with rules. Since TRAI rolled out the DLT (Distributed Ledger Technology) framework, careless campaigns get blocked at the operator level before they ever reach a handset. The practices below keep your campaigns both compliant and profitable.
1. Get Your DLT Registration Right First
Nothing else on this list matters if Airtel, Jio, Vi or BSNL refuse to carry your traffic. Under TRAI regulations, every business sending commercial SMS in India must complete these steps on an operator DLT portal:
- Principal Entity (PE) registration: a one-time company registration using your PAN, GST and business details. Registration on one operator portal (Airtel, Jio TrustID, Vi or BSNL) is recognised across the ecosystem.
- Header (sender ID) registration: the six-character alphabetic ID your messages arrive from, such as ONLSMS. Promotional headers are numeric; transactional and service headers are alphabetic.
- Content template registration: every message format must be pre-approved, with variable portions marked as {#var#}. Operators scrub each message against the registered template — a mismatch of even punctuation can cause rejection.
Budget two to five working days for approvals and register templates for every campaign type you plan to run, including regional-language versions.
2. Respect the 9 AM to 9 PM Promotional Window
TRAI permits promotional SMS only between 9:00 AM and 9:00 PM. Messages submitted outside this window are rejected or held by the operator. Two related rules trip up many first-time senders:
- Promotional messages are automatically blocked to numbers registered on the DND (Do Not Disturb) registry, which covers a large share of Indian mobile users.
- Transactional and service messages — OTPs, delivery updates, payment confirmations — can be sent 24x7 and do reach DND numbers, but only if the content genuinely matches a transactional or service template. Disguising an offer as a transactional message is a fast route to header suspension.
3. Build a Genuine Opt-In List
Purchased databases produce terrible results: high DND-block rates, near-zero conversions and complaint escalations that can get your header blacklisted. Grow your own list instead:
- Collect numbers at checkout, on lead forms and at billing counters with a clear consent statement.
- Record when and where each consent was captured — TRAI expects consent to be verifiable.
- Honour opt-outs immediately and include an opt-out route in promotional campaigns.
- Remove numbers that have failed delivery in three consecutive campaigns; they are usually inactive SIMs and you are paying for nothing.
4. Write Copy That Converts
Stay within one message part
One SMS part is 160 characters in English (GSM-7) but only 70 characters in Unicode, which includes Hindi, Tamil and every other regional script. A 220-character English message is billed as two parts, doubling campaign cost. Draft to fit one part unless the extra length clearly earns its keep.
Follow a proven structure
- Identify the brand in the first few words — recipients decide in one glance.
- Lead with the concrete benefit: "Flat 30% off till Sunday" beats "Exciting offers inside".
- One clear call to action: a short link, a phone number or a store visit — never all three.
- Add urgency honestly: a real deadline lifts response; a fake one erodes trust.
5. Time and Pace Your Campaigns
- Late morning (10 AM to 1 PM) and early evening (5 PM to 8 PM) consistently produce the best click rates for retail offers in India.
- Avoid the first day of the month for discretionary offers aimed at salaried audiences whose EMIs and bills clear then; salary-week campaigns generally outperform month-end ones.
- Cap frequency at two to four promotional messages per month per contact. Opt-outs climb sharply beyond that.
- Plan festival campaigns (Diwali, Pongal, Eid, Christmas) at least a week early — operator traffic surges can slow delivery on the festival day itself.
6. Measure What Actually Matters
- Delivery rate: a healthy campaign to a clean list should exceed 90 percent. Investigate anything lower — stale numbers, template mismatches or poor routing.
- Click-through rate: use trackable short links; 6 to 15 percent is a strong result for a relevant retail offer.
- Conversion and revenue per message: tie link clicks to orders so you can compare SMS against your other channels honestly.
- Opt-out rate: keep it under 1 percent per campaign. A spike means wrong audience, wrong frequency or wrong offer.
What Does SMS Marketing Cost in India?
At volume, promotional bulk SMS in India typically costs ₹0.10 to ₹0.20 per message, with transactional and OTP routes at roughly ₹0.15 to ₹0.25. On top of per-message rates, budget the one-time DLT registration fee (about ₹5,900 on most operator portals). Even at these prices, a campaign that converts a fraction of one percent of recipients usually pays for itself many times over — which is why disciplined list quality matters more than squeezing the last paisa off the rate. You can see current volume slabs and start a test campaign on our bulk SMS service for India page.
Frequently Asked Questions
Can I send promotional SMS at night in India?
No. TRAI restricts promotional SMS to 9 AM to 9 PM. Messages submitted outside the window are rejected or queued by the operators. Transactional and service messages such as OTPs and order updates can be sent at any hour.
What is the difference between promotional and transactional SMS?
Promotional SMS markets a product or offer, uses a numeric header, cannot reach DND numbers and is limited to the 9 AM to 9 PM window. Transactional SMS carries critical account information such as OTPs, uses an alphabetic header, reaches all numbers including DND, and works 24x7. Service messages sit in between and cover order and delivery updates to your own customers.
How many characters can one SMS contain?
One part holds 160 characters in English (GSM-7 encoding) or 70 characters in Unicode scripts such as Hindi and Tamil. Longer messages are split and billed as multiple parts of 153 and 67 characters respectively, so a 300-character English message costs two message credits.