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SMS Guidelines for India: Compliance, Message Length, and Best Practices

When sending SMS messages to India, it is essential to adhere to specific guidelines to ensure compliance and successful delivery. This guide provides vital insights for businesses and developers using the Sent API to communicate with Indian mobile users.

Two-Way SMS Support in India

Currently, two-way SMS is not supported in India. This means you can send SMS messages to users in India, but they cannot reply via SMS.

Number Portability and Message Concatenation

India supports number portability, allowing users to switch mobile carriers while keeping their phone numbers. Additionally, Sent supports concatenated messages in India, meaning if your SMS exceeds the standard 160-character limit, it will be split and reassembled on the recipient's device.

Note: Concatenation may not be supported for certain sender ID types, and message splitting can vary based on character encoding.

Message Length Limitations

The standard message length for SMS in India is 160 characters. Exceeding this limit results in the message being split into multiple segments, which are then concatenated on the recipient's device.

MMS Support

Sent does not support standard MMS (Multimedia Messaging Service) in India. Instead, multimedia content like images and videos is converted into SMS with an embedded URL, directing recipients to view the content online.

Sending SMS to Landline Numbers

SMS messages cannot be sent to landline numbers in India. Attempts to send an SMS to a landline using the Sent API will return a 400 error with error code 21614. These messages will not appear in logs, and the account will not be charged.

Compliance Considerations for International and Domestic SMS

Sent offers SMS delivery to India through both International and Domestic gateways, each with distinct compliance requirements:

International SMS

  • No DLT registration is needed.
  • Messages are sent via mobile operators' International Long Distance Operator (ILDO) connections.
  • Messages use random ILDO-approved short codes (e.g., 54321).
  • International messages bypass India's Do-Not-Disturb (DND) database, with no time-of-day restrictions.

Domestic SMS

  • DLT registration is mandatory. Companies must register their business and Sender ID on the mobile operators' Distributed Ledger Technology (DLT) portal.
  • Messages are delivered using the customer’s DLT-registered Alphanumeric Sender ID.
  • Currently, only Alphanumeric Sender IDs are supported, but Sent is considering adding support for promotional messages via DLT-approved 6-digit Sender IDs in the future.

Prohibited Content and Best Practices

When sending SMS messages to India, certain content types are prohibited:

  • Firearms
  • Gambling
  • Adult content
  • Money/loan offers
  • Political or religious content
  • Controlled substances (including cannabis)
  • Alcohol-related content
  • Messages with shortened URLs

Sent strongly advises consulting with legal counsel to ensure compliance with local laws and regulations. Here are some best practices for SMS campaigns in India:

  • Obtain opt-in consent from users before sending any communication.
  • Send messages during the recipient's daytime hours, unless urgent.
  • Ensure SMS campaigns support HELP/STOP messages in the local language.
  • Avoid contacting users on do-not-call or do-not-disturb registries.

By adhering to these guidelines and best practices, you can ensure that your SMS campaigns in India comply with local regulations and effectively reach your audience. For more information on compliance, visit the Telecom Regulatory Authority of India (TRAI) website.