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Short Message Service:A2P SMS Messaging Regulations for India

Last Updated:Sep 19, 2023

Sender ID

As per new India TRAI regulation, Sender ID registration should be done via the DLT portal

To comply with the new regulation, all enterprises need to be registered on the DLT system along with other details like Headers, Templates and Consents. Your organization will get a Unique Entity ID post registration (a fee of INR 5,900, must be paid to the operator to complete the registration process).

  • 6 digit Alpha for OTP/Transactional sms.

  • 6 digit numeric for promotional sms.

Sender ID will be prefixed with 2 letters depending on which carrier was used to deliver the SMS to the final operator.

Alpha Sender ID is not supported for International customers, and will be changed to a random short code.

DLT process introduction

1. DLT Regulations

As you might also be aware that, Telecom Regulatory Authority of India (TRAI) has released a new regulation in July 2018 to curb Unsolicited Commercial Communication (UCC) and enhance mobile subscriber privacy. TCCCPR 18 Telecom Commercial Communications Customer Preference Regulation 2018, Regulation can be downloaded files.

The Regulation is intended to eliminate spam and fraud which have been concerns for many years. The regulation has mandated the use of Blockchain technology, also known as Distributed Ledger Technology (DLT), to implement the solution.

The new regulation will affect all local traffic. Enterprises/Accounts sending domestic traffic need to register in DLT to ensure the compliance.

2. What should my customer do?

All enterprise customers registered in India for domestic termination must have their brand names/sender IDs registered with DLT. Enterprise clients can use the URL

At this preliminary stage, only the sender ID is required for registration.

Required documents for upload:

  • Scanned copy of the company PAN Share duly Scanned copy of PAN card with material details (Name of the Entity and PAN CARD number)

  • Scanned copy of Company CIN/GST/TAN Share duly Scanned copy of CIN/GST/TAN card with material details (Name of the Entity and CIN/GST/TAN number)

  • Scanned Proof of identity share duly Scanned copy of GSTIN/Aadhar or Unique Identity number/Election commission id/ Passport with material details (Name of the Entity and Identity number)

  • Proof of address share duly Scanned copy of Aadhaar/Unique Identity Number, Election Commission ID, Passport, Electricity Bill (Not Older than 3 months) with material details (Name of the Entity and Identity number)

SMS Types

India is a very complex market and there are a number of different regulations and restrictions you must comply with in order to send SMS here.

Traffic Type

Sender ID

Content Allowed


Domestic Transactional

6 digit alpha (not alphanumeric) with preregistration

Transactional traffic, OTP

No restrictions. 24/7 delivery without NDNC restrictions.

The registered Alpha Sender ID will be added with 2 letters as a prefix, depending on which carrier was used to deliver the SMS to the final operator or 2 random numbers; e.g. MD-XXXXXX (where XXXXXX is the registered Sender ID)

Domestic Promotional (none Opted-in)

Sender ID is not supported and will be changed to a random short code

Promo/Marketing content

Promo sms will be blocked to numbers registered in NDNC as per TRAI regulation.

Promo sms is only delivered between 10am-9pm IST time.

SMS outside the time range will be queued and delivered the next day.

Domestic Promotional (Opted-in)

6 digit alpha (not alphanumeric) with preregistration

This traffic can only be routed via transactional bind with opted in confirmations from each subscriber MSISDN.

24/7 delivery and without NDNC restriction.

However, handling party (customer) of the promo content must have subscriber opted in consent per each MSISDN and should provide the information to the providers handling the traffic either upfront or on demand in an event if the termination party gets a complaint from a mobile operator (mobile subscriber complaining to operator for receiving a promo content) as proof the subscriber has given consent to receive promo content. Failing to do so (not defined the actual time period) provider will be liable for penalty charges depending on the number of violations. Need to have contractual provisions in order to accept the penalty charges in case of violation.

International (transactional/Opted-in Promo)

Sender ID is not supported and will be change to a random short/long virtual number

International originated transactional content & Opted-in Promo content. (If a client registered in India, but sms originated outside India, it will be identified as international traffic.).

SMS Delivered 24/7 via International route.

No restrictions for NDNC listed numbers.

For opted in promo sms, the same Regulation apply as in for Domestic Promotional(Opted-in) listed below.

SMS headers_sender ID and definitions

Please find enclosed the explanation on type of Headers along with some examples. This will help you understand the differences between various types of messages.

1. Promotional Message

Promotional message means commercial communication that can be sent to a mobile subscriber whose preferences are not set (not on DND). Or, any commercial communication that an enterprise can send to an intended Recipient after taking consent to send such messages.


Sample SMS template1: Happiness Sale on 21 & 22 Dec. Get up to 71% OFF on over 100 brands.

Register now and get an EXTRA Rs100 OFF! Just give a missed call to 808XXXX234. T&C apply.

Sample SMS template2: 24 Hr Kitchen Furniture SALE up to 35% OFF, till 22 Dec, T&C.

Sample SMS template3: Get MY DIET by <NAME OF CONSULTANT> & lose up-to 10Kg. No exercise. No machine. First free consultation Click <URL>. To revoke consent, send SMS as REVOKE HEADER to 1909.

2. Transactional Message

Transactional message is a message that contains One Time Password (OTP) and is required to complete a banking transaction initiated by the bank customer. This is applicable to all banks including national/scheduled/private/governmental and MNC banks.

Header (6-alpha): TRUBLQ, TRUblq, TRubLQ, trouble, KLMNOP, DLTDLT, etc.

Sample SMS template1: 763892 is the OTP for tron of INR 9876.90 at ABCD App with your card XX0000. OTP is valid for 10 mins. Pls do not share it with anyone.

Sample SMS template2: 763892 is OTP for txn of INR 373.32 at ABCD on XYZ Bank Credit Card XX0000. OTPs are SECRET. DO NOT disclose it to anyone. Bank NEVER asks for OTP.

  1. Service Implicit Message

Service Implicit: Any message generated as a result of the customer's actions or his relationship with the sender that is not promotional and does not serve the customer's interest in preventing such communications will be considered as inferred consent to the service information. These messages may or may not be triggered by a subscriber-initiated transaction and will not be blocked for subscribers who have otherwise blocked service messages also. These Headers are Case Sensitive.

  • Confirmation messages of a net banking or a credit/debit transaction;

  • Product purchase confirmation; delivery status of a parcel;

  • OTP required for e-commerce website, app login, social media apps, KYC, etc. ;

  • Messages from home operator; Messages from schools regarding attendance/transport;

  • Messages from hospitals/clinics regarding appointment/discharge reports;

  • Govt. /TRAI/DoT mandated messages, advisories, messages from state Govt., LEAs, local authorities, traffic advisories, election commission, disaster management advisories;

  • Service messages from car workshops, gadget service centers;

  • Day-end/ month-end settlement alerts to securities/demat account holders.

Header (6-alpha): ABCDEF, ABCdef, ABceDF, abcdef, AFIOMA, UNFOCO, etc.

Sample SMS template1: Hello! Your A/C no. <XXXXX> has been debited by Rs. <XXXX> The A/C balance is Rs. <XXXX> on <DD/MM/YY> The A/C balance is Rs. <XXXX> Info: <TYPE>/<PURPOSE>/< Rs. of template OR REFERENCE NUMBERs.

Sample SMS template2: Dear Customer, as per your request, contact details have been updated against your fixed deposit account.

Sample SMS template3: Dear Customer, your order has been picked up by the delivery boy and is on its way. Your delicious pizza is reaching early!

4.Service Explicit Message

Any service message which does not fall under the category of service message (Implicit) will be sent only against service explicit, digitally verified/verifiable consent that has been taken from the subscriber by the respective enterprise. These Headers are Case Sensitive.

Header (6-alpha): NUTUKI, NUtuKI, NUTuki, nutuki, PRIZEM, ZSERTA, etc.

Sample SMS template1: Dear Customer, Congratulations on your Home Anniversary! Now avail a Top-up up to Rs 50 lacs* with ROI @9.20%* on your Home Loan. Call Toll Free 1800XXXXX00 *T&C.

Sample SMS template2: Dear Customer, based on your relationship, we are approving a per- approved Home Loan up to Rs. 1 crore. Click here . Regards, QT Housing. T&C.

Please note that while creating Promotional Headers on the portal, the Header should start with the number that matches the category (as per DND Preferences).

  1. Banking/Insurance/Financial products/ credit cards

  2. Real Estate

  3. Education

  4. Health

  5. Consumer goods and automobiles

  6. Communication/Broadcasting / Entertainment/IT

  7. Tourism and Leisure

  8. Food and Beverages

If an enterprise registers itself under the category "Tourism", they can register their headers as 712390, 790234, or 791919. A health based company should register its headers as 412300, 490909, etc.

PS: Govt. Headers fall under Service Implicit.