India: SMS Features & Restrictions

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.


Please be aware that there is a new regulation being implemented by Telecom Regulatory Authority of India (TRAI) which requires all domestic entities to register their entities, headers and templates. Any enterprise who fails to pre-register Distributed Ledger Technology (DLT), will become non-compliant and will not be able to send A2P SMS/Voice to the end recipient via domestic routes. International Enterprises are not affected by this change.

Phase-1 of DLT implementation which has gone live on 1st June 2020, Entity Registration and Header Registration was mandatory.
Now in the Phase-2, Entities has to start registering their Content and Consent Templates on the DLT Portal on which they have got their entities registered.

Some Highlights to be considered:- 

  • From 1st June 2020 onwards traffic of only DLT registered headers (sender id’s) would be allowed by the Telecom operators.
  • As per TRAI’s regulations, as time bands (21 hrs – 10 hrs) will be default OFF irrespective of customers registered for DND or not chosen any time band. To comply with the above guideline, we will be changing the Promotional Blockout timings on our platform to 9pm IST - 10am IST from the current blockout time of 9pm IST-9am IST.
  • As part of the DLT go live, operators will stop supporting delivery notifications for messages sent via Promotional routes with Numeric headers. No DLR’s for promotional traffic.

This is as a continuous endeavour to create a cleaner and transparent system in the India telecom industry and to curb Unsolicited Commercial Communication (UCC) along with enhanced mobile subscriber policy. The new regulation can be accessed here

We request Domestic Enterprises to register your Principal Entity, its Headers & Templates on  DLT system. Please refer to -->  How do I preregister a SenderID to INDIA

SMS Types

By default, customer will fall onto domestic promotional(non opted in) category with restrictions as mentioned below. If you are an Int'l customer or have different sms type as listed below, please contact your acc manager or write to

Traffic Type Content Allowed Sender ID Restrictions/Regulation
Domestic Transactional Transactional traffic, OTP 6 digit alpha (not alphanumeric) with DLT preregistration 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)

Promo/Marketing content

6 digit numeric with DLT pre-registration Promo sms will be blocked to numbers registered in NDNC as per TRAI regulation.

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

SMS outside the time range will be queued and delivered next day.
International (transactional/Opted-in Promo) International originated transactional content & Opt-in Promo content. (If client registered in India,but sms originated outside India, will be identified as International traffic).  Sender ID not supported and will be change to a random short/long virtual number

SMS Delivered 24/7 via International route.

No restrictions for NDNC listed numbers.

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

International Promotional (none opted in) No such origination at present moment NA NA
Domestic Promotional (opted in) This traffic can only be routed via special promo binds with opted in confirmations from each subscriber MSISDN 6 digit Alpha with DLT pre-registration 10am-9pm delivery with NDNC restriction but with alpha SID support.

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 depend on the number of violations. Please refer to Schedule IV, Article 10 --> for details. Need to have contractual provisions in order to accept the penalty charges in case of violation.


Sender ID

As per new India TRAI regulation, SenderID registration to be done via 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 might be paid to the operator to complete the registration process). 

  • 6 digit Alpha for OTP/Transactional sms
  • 6 digit numeric for promotional sms

SenderID will be prefixed with 2 letters depending on which carrier was used to deliver the SMS to the final operator. Full list of prefixes here: India Pre-registered SenderID Prefixes

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

For more information please contact your Account manager or email to


Do Not Call registry(NDNC)

Non-Optin Promo Messages sent to numbers registered in the Indian NDNC (National Do Not Call registry) list will be blocked. 


Limitation to avoid potential SMS flooding

Local regulations specify limitations to the number of messages that can be sent to the same number:

  • More than 6 messages to the same destination number within an hour with the same sender or text may be blocked
  • Users may not be able to receive more than a total of 200 SMS per day across all incoming streams.



Other features/restrictions: 


Unicode is supported.

Delivery Receipts:
Handset delivery receipts are reliable and only for Transactional traffic.  No Delivery receipts will be provided for Promotional Traffic.

Traffic restriction by political reason:

Messages towards Jammu and Kashmir networks (example, 405/55 - Airtel J&K) will be blocked by the government due to political sensitivity.

Please also note that political SMS are prohibited during election period throughout the country.


Global SMS Features Overview (Outbound only)

Global SMS Numbers Features Overview


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