23/02/2026
Understanding India's SMS Header Format (DLT Standards)
In India, all commercial and transactional SMS messages must follow a standardized header format regulated by the Telecom Regulatory Authority of India (TRAI) under DLT (Distributed Ledger Technology) guidelines. This system is designed to trace senders, categorize content, and curb the spread of SPAM and phishing.
🔹 The Anatomy of an SMS Header
A typical Indian SMS header looks like this:
XY-ABCDEF-S (e.g., VM-ICICIB-S). It is divided into three distinct functional parts.
The Prefix (The First Two Letters)
The prefix identifies the origin and the routing of the message.
First Letter: Service Provider Code
This represents the telecom operator used to fetch the message.
V: Vodafone Idea
A: Airtel
B: BSNL
J: Jio (Reliance)
D: Datacom (Videocon)
Second Letter: Service Area (Circle) Code
Contrary to common belief, the second letter usually represents the Geographic Circle (location) from which the SMS was pushed, not the message type (which is handled by the DLT template ID in the backend).
M: Mumbai
D: Delhi
K: Karnataka
T: Tamilnadu
X: (Varies by operator series)
Inbetween prefix and suffix the name of the company,vendor,bank,sender, college will be in 6 Letters et. ICICIB, NICSMS, TRAIND, BSNLCS, UNIONB ,IRSMSA, ISATHI etc,
Last Letter :
Letter – Message Type Code
Indicates the category of SMS:
P – Promotional (offers, advertisements)
S – Service (account updates, reminders)
T – Transactional (OTP, bank alerts)
G – Government (official communication)
Example: In VM-ICICIB-S, "V" stands for Vodafone and "M" stands for the Mumbai circle and "S" stands for service messages.
🔹Why It Matters ?
Confirms sender authenticity
Helps detect spam or phishing
Ensures regulatory compliance
Improves consumer protection
Always verify the header before trusting any SMS.
