Under the new DLT guidelines effective May 6, 2025, the Sender ID (also called Header or Mask) now includes a mandatory suffix that indicates the type of message being sent. This change is designed to improve transparency and help recipients identify the nature of the SMS.
Sender ID Suffix Mapping (DLT-Compliant Headers)
| Message Type | Suffix Added | Example Header |
|---|---|---|
| Promotional / Service Explicit | -P | STPL-P |
| Service Implicit | -S | STPL-S |
| Transactional | -T | STPL-T |
| Government (Exempted) | -G | STPL-G |
These suffixes are automatically appended by the DLT platform based on the approved message template type.
Key Points to Know
- No manual action is needed to add the suffix — it's handled by the DLT system.
- All A2P SMS traffic in India must comply with this format.
- Ensure your templates are correctly categorized (Transactional, Service Implicit/Explicit, Promotional) during DLT registration.
- Messages sent without proper DLT registration or incorrect headers may be blocked by telecom operators.
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