How to Stop Spam Calls and SMS on an Indian SIM — The Settings That Actually Help

Spam calls and unwanted SMS on Indian numbers come from a few distinct sources — telemarketers, unregistered promotional senders, and outright fraud attempts — and each one gets blocked through a different setting. Stacked together across your carrier, your phone, and India's official do-not-disturb system, they cover most of what reaches an Indian SIM.

Register on TRAI's DND registry first

The Telecom Regulatory Authority of India runs the National Customer Preference Register (commonly called DND). You can register by sending an SMS with "START" to 1909, calling 1909, or using the DND Complaint Centre app, and choose to block all commercial communication or just specific categories like banking or real estate promos. This mainly stops registered telemarketers, not fraud calls, but it's the foundation everything else builds on.

Report unwanted messages and calls directly to 1909

If you keep getting spam after registering on DND, forward the spam SMS to 1909 or file a complaint through the DND app with the sender's number and time received. TRAI can act against telemarketers and senders using unregistered headers, and repeated complaints against the same number carry more weight than a one-off report.

How to Formally Complain: DND Complaints vs. Reporting Fraud

A DND complaint (filed via 1909, above) and a fraud report are not the same thing, and filing the wrong one for a given call wastes the report. A DND complaint covers unwanted commercial or promotional communication from a registered telemarketer. For anything that looks like fraud instead — someone impersonating a bank, a fake KYC update request, a lottery or prize scam — the correct channel is Chakshu, a separate facility on the Department of Telecommunications' Sanchar Saathi platform (sancharsaathi.gov.in/sfc), built specifically for reporting suspected fraud communication over call, SMS, or WhatsApp. Chakshu reports are meant to be filed within 30 days of the incident to trigger an actual investigation; reports filed later still get logged but mainly feed pattern-detection rather than an individual follow-up. If you've already lost money to a scam, Chakshu is not the right first stop — report it to the national cybercrime helpline (1930) or cybercrime.gov.in instead, since that's the channel built to act on an active financial loss.

Whichever channel you use, have this ready before you start: the caller's number exactly as it appeared on your phone, the date and approximate time, whether it was a call, SMS, or WhatsApp message, and a screenshot if it was text-based. Filing with these details on hand, rather than reconstructing the timeline from memory partway through the form, is the main difference between a complaint that goes somewhere and one that doesn't.

Turn on your carrier's built-in spam detection

Jio, Airtel, and Vi all run network-level AI spam and fraud detection that flags suspicious numbers before the call even reaches you, usually visible as a warning label on the incoming call screen (Airtel calls this Spam/Fraud detection, built into the network rather than a separate app). Make sure this is enabled in your carrier's own app — for Airtel it's under the Airtel Thanks app's security section, for Jio it's part of JioSecurity — since a few of these are opt-in rather than automatic.

Configure caller ID and spam protection at the phone level

Android's Phone app (Phone by Google, the default on many phones) has its own caller ID and spam protection under Phone app Settings > Spam and Call Screen, which flags likely spam using crowdsourced reports without needing a separate app. If you use Truecaller, its usefulness comes from tuning the block settings — turn on "block silent unknown callers" and "block top spam reported numbers" rather than leaving it on default, since default settings are more conservative than most people expect.

Watch for the sender ID pattern on SMS

Legitimate transactional and promotional SMS in India use a registered DLT (Distributed Ledger Technology) sender ID, a six-character alphanumeric code like VM-HDFCBK, rather than a random 10-digit number. A bank or government-style message arriving from a plain phone number is a strong signal it's not from who it claims to be, regardless of what the message text says.

Block manually as the last layer

For numbers that get through everything else, block them directly from the call log or messages app — Android lets you block and report as spam in one step, which also feeds that number into the crowdsourced spam database used by others. This won't stop a spammer from calling with a new number, but it does clean up your own experience immediately.

Checking Whether SIMs Are Fraudulently Issued in Your Name

A less obvious source of scam calls is SIMs fraudulently issued against a stolen identity, sometimes yours. The government's Sanchar Saathi portal (sancharsaathi.gov.in) lets you check how many mobile connections are currently registered against your ID and request disconnection of any you don't recognize. Running this check periodically, not just when you suspect a problem, catches identity misuse before it escalates into something used for scam calls under your own name.

Registering on DND, enabling carrier-side detection, and tuning your phone's spam filter each close off a different slice of the problem — stacked together, they block the overwhelming majority of what reaches an Indian SIM. Layer these settings together and most of the daily noise stops on its own.