What Are the Consent Requirements for Different Types of SMS Messages in India?

1. 2-Way SMS Consent Requirements

2-way SMS allows businesses to both send and receive messages from customers. Unlike other types, it enables direct interaction, making it ideal for customer support, queries, and engagement. To send 2-way SMS in India, businesses must meet the following requirements:

Example:

Sender: MYBANKCO Message: “Hi Riya, your recent transaction of ₹100 was successful. For inquiries, reply to this SMS or call our helpline.” This message is clear, informative, and enables two-way communication.

• Register as a Principal Entity (business, legal, or government organization)
• Use a registered sender ID (header) with up to 11 alphanumeric characters (e.g., VD-KOTAKB)
• Get message content templates approved on the DLT platform
• Register customer consent through a DLT consent template
• This type of messaging requires proper consent tracking because customers may respond directly.

2. Transactional SMS Consent Requirements

Transactional SMS includes messages that provide important information related to a service or transaction. These messages are non-promotional and are critical for user experience. According to TRAI SMS regulations, transactional messages have more relaxed consent requirements:

Example:

Sender: BRNDID Message: “Your order #123456 has been confirmed. You will receive delivery updates via SMS.” Because the user initiated the interaction, implied consent applies here.

• Implied consent is sufficient
• No opt-out option is required
• No time restrictions (can be sent anytime)
• Messages can be sent to DND (Do Not Disturb) numbers
• A 6-character sender ID representing the brand is mandatory
• These messages are typically triggered by user actions, such as purchases, OTP requests, or account updates

3. Promotional SMS Consent Requirements

Promotional SMS is used to market products, services, or offers. This includes discounts, campaigns, surveys, and newsletters. This category has the strictest consent requirements under SMS compliance in India:

Example:

Sender: TXTSAL Message: “Get 20% off on all products this weekend! Shop now. To unsubscribe, reply STOP.” These rules ensure that users are not spammed and have full control over promotional communication.

• Express written consent is mandatory
• Messages can only be sent between 9 AM and 9 PM
• DND numbers must be excluded
• A 6-digit sender ID with an operator-defined prefix is required
• Businesses must clearly mention:
• Purpose of messages
• Frequency of communication
• Terms and conditions
• Privacy policy
• An easy opt-out option (e.g., “Reply STOP”) must be included

Conclusion

Understanding the consent requirements for different types of SMS messages is crucial for staying compliant with TRAI guidelines and running effective campaigns. While transactional SMS relies on implied consent, promotional SMS requires explicit user permission. Meanwhile, 2-way SMS adds an interactive layer but still requires proper registration and consent tracking through DLT. At Celitix, we help businesses navigate SMS compliance in India, manage DLT registration, and build high-performing messaging strategies. By following the right consent practices, you can ensure better deliverability, higher engagement, and long-term customer trust.