Find out who sent that SMS
Every commercial SMS in India carries a sender ID in the same shape. Once you can read it, you can tell in a second whether a message even went through the system that is supposed to police it.
Copy it from the very top of the message. Typing sends nothing — pressing See sender sends the sender ID, and nothing else, to check it against the registry.
How to read an Indian sender ID
AX
Who carried it
Two letters, assigned by TRAI. The first is the phone operator the message was sent through; the second is the licensed area it was sent from.
ENFOLD
Who registered it
Up to eleven characters — six in almost every message you will see — chosen by the company and registered against its identity documents.
S
What kind of message
Added by the operator, not by the sender, from the template the message was registered under. It is the one part nobody sending the message controls.
What a valid sender ID does not prove
Registering a sender ID is paperwork. Criminals complete it, and messages from registered senders are used in fraud every day in India. A sender ID that reads correctly tells you the message travelled a registered route — it tells you nothing about whether what it says is true, and nothing about whether the link in it is safe.
Check the message itself →The operator letter
The operator letter
The first letter of the two-letter prefix.
| Letter | Meaning |
|---|---|
| A | Bharti Airtel / Bharti Hexacom |
| B | Bharat Sanchar Nigam Ltd (BSNL) |
| C | V-CON Mobile & Infra |
| D | Aircel / Dishnet Wireless |
| E | Reliance Telecom |
| J | Reliance Jio Infocomm |
| M | Mahanagar Telephone Nigam Ltd (MTNL) |
| Q | Quadrant Televentures |
| R | Reliance Communications |
| T | Tata Teleservices |
| V | Vodafone Idea |
The service-area letter
The second letter. It is where the sender is registered, not where you are.
| Letter | Meaning |
|---|---|
| A | Andhra Pradesh |
| B | Bihar |
| D | Delhi |
| E | UP-East |
| G | Gujarat |
| H | Haryana |
| I | Himachal Pradesh |
| J | Jammu & Kashmir |
| K | Kolkata |
| L | Kerala |
| M | Mumbai |
| N | North East |
| O | Orissa |
| P | Punjab |
| R | Rajasthan |
| S | Assam |
| T | Tamil Nadu (incl. Chennai) |
| V | West Bengal |
| W | UP-West |
| X | Karnataka |
| Y | Madhya Pradesh |
| Z | Maharashtra |
The category letter
Added by the operator since 6 May 2025, from the template the message was registered under.
| Letter | Meaning |
|---|---|
| T | Transactional — One-time passwords and messages tied to a transaction you initiated. |
| S | Service — Account and service updates from a company you already deal with. |
| P | Promotional — Marketing. It cannot carry an OTP and you can opt out of it. |
| G | Government — Sent under a government or regulatory authorisation. |
Reserved number series
Calls, not messages — but the same question, so they belong here.
| Starts with | Meaning |
|---|---|
| 140 | Promotional calls from registered telemarketers. |
| 1600 | Transactional and service calls from registered entities. |
| 160 | Government bodies, regulators and financial institutions calling the public. |
TRAI — Headers assigned by the Access Providers to Principal Entities · trai.gov.in